1
|
Niu Z, Zhao Y, Zhang Q, Zhao Z, Ge D, Zhou J, Xu Y. Suppression of cracking in drying colloidal suspensions with chain-like particles. J Chem Phys 2024; 160:164901. [PMID: 38656445 DOI: 10.1063/5.0203112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/03/2024] [Indexed: 04/26/2024] Open
Abstract
The prevention of drying-induced cracking is crucial in maintaining the mechanical integrity and functionality of colloidal deposits and coatings. Despite exploring various approaches, controlling drying-induced cracking remains a subject of great scientific interest and practical importance. By introducing chain-like particles composed of the same material and with comparable size into commonly used colloidal suspensions of spherical silica nanoparticles, we can significantly reduce the cracks formed in dried particle deposits and achieve a fivefold increase in the critical cracking thickness of colloidal silica coatings. The mechanism underlying the crack suppression is attributed to the increased porosity and pore sizes in dried particle deposits containing chain-like particle, which essentially leads to reduction in internal stresses developed during the drying process. Meanwhile, the nanoindentation measurements reveal that colloidal deposits with chain-like particles exhibit a smaller reduction in hardness compared to those reported using other cracking suppression approaches. This work demonstrates a promising technique for preparing colloidal coatings with enhanced crack resistance while maintaining desirable mechanical properties.
Collapse
Affiliation(s)
- Zhaoxia Niu
- School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China
| | - Yiping Zhao
- Institute for Engineering and Technology, Xinxing Cathay International Group, Shanghai 201403, China
| | - Qiuting Zhang
- School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China
| | - Zhiyuan Zhao
- Wenzhou Institute, University of Chinese Academy of Science, Wenzhou, Zhejiang 325000, China
| | - Dengteng Ge
- Institute for Engineering and Technology, Xinxing Cathay International Group, Shanghai 201403, China
| | - Jiajia Zhou
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Ye Xu
- School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China
| |
Collapse
|
2
|
Bhattacharjee S, Srivastava S. Ordered stripes to crack patterns in dried particulates of DNA-coated gold colloids via modulating nanoparticle-substrate interactions. Soft Matter 2023; 19:2265-2274. [PMID: 36919352 DOI: 10.1039/d2sm01446g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The surface pattern in dried droplets of nanoparticle suspension possesses direct correlation with the evaporation profile, which apart from the bulk parameters, can also be altered by tuning the nanoscale interactions. Here, we show that, for sessile drops of DNA-coated gold nanoparticle (DNA-AuNP) solution, the alteration in evaporation pathway of TPCL (three-phase contact line) from stick-slip to mixed mode leads to a surface morphological transition from concentric rings with stripes to radial crack formation within the coffee ring deposit. A freshly cleaned silicon substrate offers hydrophilic/favorable substrate-nanoparticle interaction and produces multiple ordered stripes due to stick-slip motion of the TPCL. Using a SiO2/Si substrate with ∼200 nm of oxide layer leads to an increase in the initial water contact angle θi-w by ∼40°, due to increased hydrophobicity of the substrate. Three distinct modes of evaporation are observed - constant contact radius (CCR), constant contact angle (CCA) and mixed mode, resulting in the formation of radial cracks on a thick coffee ring structure. The critical thickness (hc), beyond which the cracks start to appear, was measured to be ∼600 nm and is in close agreement with the theoretical estimate of ∼510 nm. Through in situ contact angle and ex situ SEM measurements, we provide an understanding of the observed surface morphological transition in the dried particulate at various nanoparticle densities. Further analysis of the coffee ring width (d), linear crack density (σ) and crack spacing (λ) provides insight into the mechanism of crack formation for droplets dried on oxide-coated substrates.
Collapse
Affiliation(s)
- Suman Bhattacharjee
- Centre for Research in Nanotechnology & Science (CRNTS), Indian Institute of Technology Bombay, Mumbai-400 076, India
- Soft Matter and Nanomaterials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Mumbai-400 076, India.
| | - Sunita Srivastava
- Soft Matter and Nanomaterials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Mumbai-400 076, India.
| |
Collapse
|
3
|
Lee Y, Kim J, Lee S, Wooh S, Yoon H, Char K. Cracking of Colloidal Films to Generate Rectangular Fragments. Langmuir 2022; 38:4935-4941. [PMID: 35404063 DOI: 10.1021/acs.langmuir.2c00328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cracks are common in nature. Cracking is known as an irreversible and uncontrollable process. To control the cracking patterns, many researchers have proposed methods to prepare notches for stress localization on films. In this work, we investigate a method of controlling cracks by making microscale pyramid patterns that have notches between the pyramids. After preparing pyramid patterns consisting of colloidal particles with organic residue, we annealed them to induce volume shrinkage and cracking between the pyramids. We studied the effect of film thickness on cracking and the generation of rectangular fragments consisting of multiple pyramids. The area of rectangular fragments was in good agreement with the results of scaling analysis. The concept of controlling cracks by imprinting notches on a film and the relationship with the film thickness can guide the study of cracking phenomena.
Collapse
Affiliation(s)
- Yunchan Lee
- The National Creative Research Initiative Center for Intelligent Hybrids, The World Class University Program for Chemical Convergence for Energy and Environment, School of Chemical and Biological Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Jaekyoung Kim
- Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Soojin Lee
- The National Creative Research Initiative Center for Intelligent Hybrids, The World Class University Program for Chemical Convergence for Energy and Environment, School of Chemical and Biological Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Sanghyuk Wooh
- School of Chemical Engineering & Materials Science, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Hyunsik Yoon
- Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Kookheon Char
- The National Creative Research Initiative Center for Intelligent Hybrids, The World Class University Program for Chemical Convergence for Energy and Environment, School of Chemical and Biological Engineering, Seoul National University, Seoul 08826, Republic of Korea
| |
Collapse
|
4
|
Badar A, Tirumkudulu MS. Moving cracks in drying colloidal films. Soft Matter 2022; 18:2252-2275. [PMID: 35244102 DOI: 10.1039/d1sm01568k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Drying colloidal films are encountered in many applications ranging from paints and coatings to ceramic and semiconductor processing. In many cases, shrinkage stresses are generated during drying, which can fracture the film. While much of the previous experimental and theoretical work has focused on cracking in static cracks, there are very few studies on the dynamics of cracks in colloidal coatings. Here, we derive an analytical solution for the stress, displacement, and pressure fields near the crack tip for a steadily moving crack. We consider first the two extreme cases, namely, the undrained limit where the crack motion is much faster than the Darcy flow rate and the opposite extreme of very slow crack propagation, the drained limit. Next, we consider the general case where the timescale for crack-tip motion is comparable to that for the interstitial flow. The results incorporate the micro-structural details of the system including the particle volume fraction and nature of packing, and the mechanical properties of the particles such as shear modulus and Poisson's ratio. While the predicted results are in line with those for brittle materials, the predicted crack speeds are at least an order of magnitude higher than those observed in experiments. We conclude with the possible reasons for the discrepancy.
Collapse
Affiliation(s)
- Atiya Badar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
| | - Mahesh S Tirumkudulu
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
| |
Collapse
|
5
|
Abstract
Cracks generated due to desiccation of wet colloidal systems are ubiquitous, examples being nanomaterial films, painted walls, cemented floors, mud fields, river beds, and even giant rocks. In all such cases, crack patterns are often appreciably similar but for the length and time scales, which can be widely differing. In this work, we have examined the crack formation more closely to see if there exists some generality with regard to the length scale of parameters and the formation time. Specifically, using a commonly used colloidal dispersion and optimized conditions to form polygonal network patterns rather than isolated cracks (films of subcritical thickness), we have studied the time evolution of the pattern parameters, the area occupied by the cracks, their lengths, and the widths. As is well known, initially, a network of cracks forms, which we term as the primary generation, followed by interconnecting cracks inside the polygonal regions (secondary) and, later, cracks spreading in local regions (tertiary). We find that the area and the width increase nearly linearly with time with the change in the slope corresponding to the change in the generation. When normalized with respect to the final values, the trends obtained for different film thicknesses overlap, the only exception being the pattern containing unconnected cracks. Thus, the time evolution of cracks is shown to be predictable based on width filtering. Including the angle between cracks as further input into the recursive model, the possibility of identifying the hierarchy of crack segments is also shown. The approach may be useful in determining the age, authenticity, and details of old paintings, understanding the stress profile of geological rocks, and analyzing various natural and manmade hierarchical structures.
Collapse
Affiliation(s)
- Ankush Kumar
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| | - G U Kulkarni
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| |
Collapse
|
6
|
|
7
|
Cai Z, Li Z, Ravaine S, He M, Song Y, Yin Y, Zheng H, Teng J, Zhang A. From colloidal particles to photonic crystals: advances in self-assembly and their emerging applications. Chem Soc Rev 2021; 50:5898-5951. [PMID: 34027954 DOI: 10.1039/d0cs00706d] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Over the last three decades, photonic crystals (PhCs) have attracted intense interests thanks to their broad potential applications in optics and photonics. Generally, these structures can be fabricated via either "top-down" lithographic or "bottom-up" self-assembly approaches. The self-assembly approaches have attracted particular attention due to their low cost, simple fabrication processes, relative convenience of scaling up, and the ease of creating complex structures with nanometer precision. The self-assembled colloidal crystals (CCs), which are good candidates for PhCs, have offered unprecedented opportunities for photonics, optics, optoelectronics, sensing, energy harvesting, environmental remediation, pigments, and many other applications. The creation of high-quality CCs and their mass fabrication over large areas are the critical limiting factors for real-world applications. This paper reviews the state-of-the-art techniques in the self-assembly of colloidal particles for the fabrication of large-area high-quality CCs and CCs with unique symmetries. The first part of this review summarizes the types of defects commonly encountered in the fabrication process and their effects on the optical properties of the resultant CCs. Next, the mechanisms of the formation of cracks/defects are discussed, and a range of versatile fabrication methods to create large-area crack/defect-free two-dimensional and three-dimensional CCs are described. Meanwhile, we also shed light on both the advantages and limitations of these advanced approaches developed to fabricate high-quality CCs. The self-assembly routes and achievements in the fabrication of CCs with the ability to open a complete photonic bandgap, such as cubic diamond and pyrochlore structure CCs, are discussed as well. Then emerging applications of large-area high-quality CCs and unique photonic structures enabled by the advanced self-assembly methods are illustrated. At the end of this review, we outlook the future approaches in the fabrication of perfect CCs and highlight their novel real-world applications.
Collapse
Affiliation(s)
- Zhongyu Cai
- Research Institute for Frontier Science, Beijing Advanced Innovation Center for Biomedical Engineering, School of Space and Environment, Beihang University, Beijing 100191, China. and Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576, Singapore and Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Zhiwei Li
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - Serge Ravaine
- CNRS, Univ. Bordeaux, CRPP, UMR 5031, F-33600 Pessac, France
| | - Mingxin He
- Department of Physics, Center for Soft Matter Research, New York University, New York, NY 10003, USA
| | - Yanlin Song
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Yadong Yin
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - Hanbin Zheng
- CNRS, Univ. Bordeaux, CRPP, UMR 5031, F-33600 Pessac, France
| | - Jinghua Teng
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634, Singapore.
| | - Ao Zhang
- Research Institute for Frontier Science, Beijing Advanced Innovation Center for Biomedical Engineering, School of Space and Environment, Beihang University, Beijing 100191, China.
| |
Collapse
|
8
|
Lama H, Gogoi T, Basavaraj MG, Pauchard L, Satapathy DK. Synergy between the crack pattern and substrate elasticity in colloidal deposits. Phys Rev E 2021; 103:032602. [PMID: 33862708 DOI: 10.1103/physreve.103.032602] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 02/05/2021] [Indexed: 11/07/2022]
Abstract
Desiccation cracks in colloidal deposits occur to release the excess strain energy arising from the competition between the drying induced shrinkage of the deposit and its adhesion to the substrate. Here we report remarkably different morphology of desiccation cracks in the dried patterns formed by the evaporation of sessile drops containing colloids on elastomer (soft) or glass (stiff) substrates. The change in the crack pattern, i.e., from radial cracks on stiff substrates to circular cracks on soft substrates, is shown to arise solely due to the variation in elasticity of the underlying substrates. Our experiments and calculations reveal an intricate correlation between the desiccation crack patterns and the substrate's elasticity. The mismatch in modulus of elasticity between the substrate and that of the particulate deposit significantly alters the energy release rate during the nucleation and propagation of cracks. The stark variation in crack morphology is attributed to the tensile or compressive nature of the drying-induced in-plane stresses.
Collapse
Affiliation(s)
- Hisay Lama
- Soft Materials Laboratory, Department of Physics, IIT Madras, Chennai-600036, India.,Department of Chemical Engineering, IIT Madras, Chennai-600036, India.,IBS Center for Soft and Living Matter, UNIST, Ulsan-44919, South Korea
| | - Tonmoy Gogoi
- Soft Materials Laboratory, Department of Physics, IIT Madras, Chennai-600036, India
| | | | - Ludovic Pauchard
- Laboratoire FAST, Université Paris-Sud, CNRS, Université Paris-Saclay, F-91405, Orsay, France
| | - Dillip K Satapathy
- Soft Materials Laboratory, Department of Physics, IIT Madras, Chennai-600036, India
| |
Collapse
|
9
|
Affiliation(s)
- Masato Yamamura
- Department of Applied Chemistry Kyushu Institute of Technology Kitakyushu Japan
| |
Collapse
|
10
|
Franks GV, Sesso ML, Lam M, Lu Y, Xu L. Elastic plastic fracture mechanics investigation of toughness of wet colloidal particulate materials: Influence of saturation. J Colloid Interface Sci 2021; 581:627-634. [PMID: 32810728 DOI: 10.1016/j.jcis.2020.07.142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/16/2020] [Accepted: 07/29/2020] [Indexed: 10/23/2022]
Abstract
HYPOTHESIS Previous use of linear elastic fracture mechanics to estimate toughness of wet particulate materials underestimates the toughness because it does not account for plastic deformation as a dissipation mechanism. Plastic deformation is responsible for the majority of energy dissipated during the fracture of wet colloidal particulate materials. Plastic deformation around the crack tip increases with saturation of the particulate body. The toughness of the body increases with increasing saturation. EXPERIMENTS Elastic plastic fracture mechanics using the J-integral approach was used for the first time to measure the fracture toughness (JIC) of wet micron sized alumina powder bodies as a function of saturation. The samples were prepared by slip casting. The saturation was controlled by treatment in a humidity chamber. The elastic modulus (E) and the energy dissipated by plastic flow (Apl) were measured in uniaxial compression. The critical stress intensity factor (KIC) was measured using a diametral compression sample with a flaw of known size. The fracture toughness (JIC) was calculated from these measured quantities and the geometry of the specimen. FINDINGS Elastic plastic fracture mechanics was used for the first time to quantitively account for plastic deformation of wet particulate materials. The linear elastic fracture mechanics approach previously used accounted for less than 1% of the total energy dissipated in fracture. Toughness (JIC) was found to increase with increasing saturation due to plastic deformation that increased with saturation level. The improved understanding of toughness as a function of saturation will aid in providing quantitative analysis of cracking in drying colloidal films and bodies.
Collapse
Affiliation(s)
- George V Franks
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia.
| | - Mitchell L Sesso
- Department of Engineering, School of Engineering and Mathematical Sciences, College of Science, Health and Engineering, La Trobe University, Vic 3086, Australia
| | - Matthew Lam
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia
| | - Yi Lu
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia
| | - Liqing Xu
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia
| |
Collapse
|
11
|
Meng W, Liu M, Gan Y, Pauchard L, Chen CQ. Cracking to curling transition in drying colloidal films. Eur Phys J E Soft Matter 2020; 43:64. [PMID: 33009958 DOI: 10.1140/epje/i2020-11985-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Drying-induced cracking is widely encountered in nature and is of fundamental interest in industrial applications. During desiccation, the evolution of water content is nonlinear. Considering the inhomogeneous procedure of desiccation, it is worth considering whether water content will affect the crack pattern formation. To address this concern, in this paper, we report an experimental investigation on the effect of water content on the failure mode in drying colloidal films. A distinct failure transition from random cracking to curling is found when the initial water content increases gradually. When the water content is below a critical value for given film thickness, random desiccation cracking driven by shrinkage is observed. Beyond this critical water content, the film curls with the advent of several main cracks. It is also found that the critical water content corresponding to the transition point depends on the film thickness. In order to qualitatively interpret the experimental observation, a theoretical model is established by adopting the fracture mechanics based on the energy method. The model is found to agree well with the experimental results, elucidating the effects of initial water content on the crack patterns and the transition of failure modes.
Collapse
Affiliation(s)
- Weipeng Meng
- Department of Engineering Mechanics, CNMM & AML, Tsinghua University, 100084, Beijing, China
| | - Mingchao Liu
- Department of Engineering Mechanics, CNMM & AML, Tsinghua University, 100084, Beijing, China
- Mathematical Institute, University of Oxford, OX2 6GG, Oxford, UK
| | - Yixiang Gan
- School of Civil Engineering, The University of Sydney, NSW 2006, Sydney, Australia
| | | | - C Q Chen
- Department of Engineering Mechanics, CNMM & AML, Tsinghua University, 100084, Beijing, China.
| |
Collapse
|
12
|
Jiang Z, Hsain Z, Pikul JH. Thick Free-Standing Metallic Inverse Opals Enabled by New Insights into the Fracture of Drying Particle Films. Langmuir 2020; 36:7315-7324. [PMID: 32501700 DOI: 10.1021/acs.langmuir.0c00761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Metallic inverse opals are porous materials with enhanced mechanical, chemical, thermal, and photonic properties used to improve the performance of many technologies, such as battery electrodes, photonic devices, and heat exchangers. Cracking in the drying opal templates used to fabricate inverse opals, however, is a major hindrance to the use of these materials for practical and fundamental studies. In this work, we conduct desiccation experiments on polystyrene particle opals self-assembled on indium-tin oxide coated substrates to study their fracture mechanisms, which we describe using an energy-conservation fracture model. The model incorporates film yielding, particle order, and interfacial friction to explain several experimental observations, including thickness-dependent crack spacings, cracking stresses, and order-dependent crack behavior. Guided by this model, we are the first to fabricate 120 μm thick free-standing metallic inverse opals, which are 4 times thicker than previously reported non-free-standing metallic inverse opals. Moreover, by controlling cracks, we achieve a crack-free single-crystal domain up to 1.35 mm2, the largest ever reported in metallic inverse opals. This work improves our understanding of fracture mechanics in drying particle films, provides guidelines to reduce crack formation in opal templates, and enables the fabrication of free-standing large-area single-crystal inverse opals.
Collapse
Affiliation(s)
- Zhimin Jiang
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Zakaria Hsain
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - James H Pikul
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
13
|
Xue S, Jiang XF, Zhang G, Wang H, Li Z, Hu X, Chen M, Wang T, Luo A, Ho HP, He S, Xing X. Surface Plasmon-Enhanced Optical Formaldehyde Sensor Based on CdSe@ZnS Quantum Dots. ACS Sens 2020; 5:1002-1009. [PMID: 32181650 DOI: 10.1021/acssensors.9b02462] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
For the first time, a reproducible surface plasmon-enhanced optical sensor for the detection of gaseous formaldehyde was proposed, which was fabricated by depositing a mixture of CdSe@ZnS quantum dots (QDs), fumed silica (FS), and gold nanoparticles (GNs) on the surface of a silica sphere array to meet the urgent requirement of a rapid, sensitive, and highly convenient formaldehyde detection method. Because of the spectral overlap between QDs and GNs, plasmon-enhanced fluorescence was observed in the film of QDs/FS/GNs. When exposed to formaldehyde molecules, the enhanced fluorescence was quenched linearly with the increase of formaldehyde concentration in the range of 0.5-2.0 ppm. The reason is attributed to the nonradiative electron transfer from QDs to the carbonyl of formaldehyde molecules with the assistance of amino groups. Our results demonstrate that the designed sensors are capable of detecting ultralow concentration gaseous formaldehyde at room temperature with a fast response-recovery time and excellent selectivity, stability, and reproducibility. This work provides a simple and low-cost approach for optical formaldehyde sensor fabrication and shows promising applications in environmental detection.
Collapse
Affiliation(s)
- Sheng Xue
- College of Biophotonics, South China Normal University, Guangzhou 510006, China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Xiao-Fang Jiang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Geng Zhang
- School of Electronic Engineering and Intelligentization, Dongguan University of Technology, Dongguan 523808, China
| | - Haiyan Wang
- School of Information Technology, Guangdong Industry Polytechnic, Guangzhou 510330, China
| | - Zongbao Li
- School of Material and Chemical Engineering, Tongren University, Tongren 554300, China
| | - Xiaowen Hu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Mingyu Chen
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Tianci Wang
- College of Biophotonics, South China Normal University, Guangzhou 510006, China
| | - Aiping Luo
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Ho-pui Ho
- Department of Biomedical Engineering, The Chinese University of Hong Kong, New Territories, Hong Kong SAR 999077, China
| | - Sailing He
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Xiaobo Xing
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| |
Collapse
|
14
|
Abstract
Thin films of polymer coatings have important industrial applications ranging from paints and coatings to pharmaceuticals. In many applications, the coatings are obtained by applying thin films of dilute polymer solutions, wherein the solvent evaporates to leave behind a thin polymer film. In some cases, the thin films may crack due to shrinkage stresses developed during drying. While a number of studies have focused on the stress development, the phenomenon of cracking in polymer films is not fully investigated. In the present work, thin films of a silicone polymer solution were cast on substrates of varying Young's moduli and investigated for cracking as a function of film thickness and substrate modulus. Micro-Raman spectroscopy measurements show that thin films dry uniformly while thick films form a skin at the top surface leading to slow drying rates. Transverse stresses were measured using the cantilever technique and related to the extent of cracking in the film. We investigated the influence of substrate rigidity on the cracking behavior and found that decreasing the stiffness of the substrate increases the extent of cracking.
Collapse
Affiliation(s)
- Bhawana Singh Tomar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
| | | | | |
Collapse
|
15
|
Lohani D, Basavaraj MG, Satapathy DK, Sarkar S. Coupled effect of concentration, particle size and substrate morphology on the formation of coffee rings. Colloids Surf A Physicochem Eng Asp 2020; 589:124387. [DOI: 10.1016/j.colsurfa.2019.124387] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
16
|
Pujar R, Kumar A, Rao KDM, Sadhukhan S, Dutta T, Tarafdar S, Kulkarni GU. Narrowing Desiccating Crack Patterns by an Azeotropic Solvent for the Fabrication of Nanomesh Electrodes. Langmuir 2019; 35:16130-16135. [PMID: 31710498 DOI: 10.1021/acs.langmuir.9b02442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Desiccation of a colloidal layer produces crack patterns because of stress arising out of solvent evaporation. Associated with it is the rearrangement of particles, while adhesion to the substrate resists such movements. The nature of solvent, which is often overlooked, plays a key role in the process as it dictates evaporation and wetting properties of the colloidal film. Herein, we study the crack formation process by using a mixture of solvents, water, and isopropyl alcohol (IPA). Among the various ratios, a water/IPA mixture (15:85 by volume) close to the azeotropic composition possesses unusual evaporation and wetting properties, leading to narrower cracks with widths down to ∼162 nm, uncommon among the known crackle patterns. The dense and narrow crack patterns have been used as sacrificial templates to obtain metal meshes on transparent substrates for optoelectronic applications.
Collapse
Affiliation(s)
- Rajashekhar Pujar
- Centre for Nano and Soft Matter Sciences , Jalahalli , Bengaluru 560013 , India
- Manipal Academy of Higher Education , Manipal 576104 , India
| | - Ankush Kumar
- Centre for Nano and Soft Matter Sciences , Jalahalli , Bengaluru 560013 , India
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur , Bengaluru 560064 , India
| | - K D M Rao
- Technical Research Center , Indian Association for the Cultivation of Science , Kolkata 700032 , India
| | - Supti Sadhukhan
- Physics Department , Jogesh Chandra Chaudhuri College , Kolkata 700033 , India
| | - Tapati Dutta
- Physics Department , St. Xavier's College , Kolkata 700016 , India
| | - Sujata Tarafdar
- Physics Department , Jadavpur University , Kolkata 700032 , India
| | - Giridhar U Kulkarni
- Centre for Nano and Soft Matter Sciences , Jalahalli , Bengaluru 560013 , India
| |
Collapse
|
17
|
Romasanta LJ, D’alençon L, Kirchner S, Pradère C, Leng J. Thin Coatings of Cerium Oxide Nanoparticles with Anti-Reflective Properties. Applied Sciences 2019; 9:3886. [DOI: 10.3390/app9183886] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cerium oxide, in addition to its catalytic properties, is also known for its optical properties such as ultraviolet (UV) radiation filtering and a relatively high refractive index ( n > 2 ), which makes it an excellent candidate for multifunctional coatings. Here, we focus on the optical properties of thin deposits (≲2 μ m) of densely packed C e O 2 nanoparticles, which we assemble using two evaporation-based techniques: convective self-assembly (CSA, a type of very slow blade-coating) to fabricate large-scale coatings of controllable thickness—from tens of nanometres to a few micrometers—and microfluidic pervaporation which permits us to add some micro-structure to the coatings. Spectroscopic ellipsometry yields the refractive index of the resulting nano-porous coatings, which behave as lossy dielectrics in the UV-visible regime and loss-less dielectrics in the visible to infra-red (IR) regime; in this regime, the fairly high refractive index (≈1.8) permits us to evidence thickness-tunable anti-reflection on highly refractive substrates, such as silicon, and concomitant enhanced transmissions which we checked in the mid-IR region.
Collapse
|
18
|
Mizuguchi T, Inasawa S. Flow of condensed particles around a packing front visualized by drying colloidal suspensions on a tilted substrate. Soft Matter 2019; 15:4019-4025. [PMID: 31041983 DOI: 10.1039/c9sm00280d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A gravity effect was demonstrated for 10 nm particles drying in colloidal suspensions. The particles were well-dispersed and did not sediment. However, when a suspension was dried on a tilted directional cell, a clear downward flow of particles was observed around the packing front, which was the boundary between the packed particles layer and the suspension. Three particle sizes (10-110 nm) were examined, with the most pronounced effect being on the 10 nm particles. The primary origin of the downflow was attributed to condensation of particles near the packing front and the subsequent increase in the overall density of the condensed layer. Because of the flow, the packing front was not parallel to the drying interface and tilted cracks formed in the packed layer. A mathematical model was proposed that considered conservation of the suspended particles in the condensed layer. Three competing factors of particle transport (advection, particle consumption by packing, and particle transport by the downward flow) were used to explain the experimental results. Overall, the results suggested that simple substrate tilting would be useful to evaluate whether suspended particles are easily packed or not during drying.
Collapse
Affiliation(s)
- Takuho Mizuguchi
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
| | | |
Collapse
|
19
|
Bouchaudy A, Salmon JB. Drying-induced stresses before solidification in colloidal dispersions: in situ measurements. Soft Matter 2019; 15:2768-2781. [PMID: 30734814 DOI: 10.1039/c8sm02558d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We first report an original setup that enables continuous measurements of stresses induced by the drying of confined drops of complex fluids. This setup is mainly based on a precision scale working with an electromagnetic force compensation technique that provides accurate measurements of forces, while allowing simultaneously controlled evaporation rates, in situ microscopic observations, and thus quantitative estimates of normal stresses. We then performed an extensive study of the drying of a charged colloidal dispersion using this setup. Stress measurements clearly show the emergence of large tensile stresses during drying, well-before the solidification stage evidenced by the invasion of the porous colloidal material by air. Combined measurements of solid deformation and concentration profiles (particle tracking, Raman micro-spectroscopy) help us to demonstrate that these stresses are due to the formation of a solid at a low volume fraction, which further undergoes drying-induced shear deformations up to the colloid close-packing, as also supported by large deformation poroelastic modeling. Above all, our results highlight the importance of repulsive colloidal interactions in the build-up of mechanical stresses during drying.
Collapse
Affiliation(s)
- Anne Bouchaudy
- CNRS, Solvay, LOF, UMR 5258, Univ. Bordeaux, F-33600 Pessac, France.
| | | |
Collapse
|
20
|
Léang M, Lairez D, Cousin F, Giorgiutti-Dauphiné F, Pauchard L, Lee LT. Structuration of the Surface Layer during Drying of Colloidal Dispersions. Langmuir 2019; 35:2692-2701. [PMID: 30719921 DOI: 10.1021/acs.langmuir.8b03772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
During evaporative drying of a colloidal dispersion, the structural behavior at the air-dispersion interface is of particular relevance to the understanding of the consolidation mechanism and the final structural and mechanical properties of the porous media. The drying interface constitutes the region of initial drying stress that, when accumulated over a critical thickness, leads to crack formation. This work presents an experimental study of top-down drying of colloidal silica dispersions with three different sizes (radius 5, 8, and 13 nm). Using specular neutron reflectivity, we focus on the structural evolution at the free drying front of the dispersion with a macroscopic drying surface and demonstrate the existence of a thick concentrated surface layer induced by heterogeneous evaporation. The reflectivity profile contains a strong structure peak due to scattering from particles in the interfacial region, from which the interparticle distance is deduced. A notable advantage of these measurements is the direct extraction of the corresponding dispersion concentration from the critical total reflection edge, providing a straightforward access to a structure-concentration relation during the drying process. The bulk reservoir of this experimental configuration renders it possible to verify the evaporation-diffusion balance to construct the surface layer and also to check reversibility of particle ordering. We follow the structural evolution of this surface layer from a sol to a soft wet-gel that is the precursor of a fragile skin and the onset of significant particle aggregation that precedes formation of the wet-crust. Separate complementary measurements on the structural evolution in the bulk dispersion are also carried out by small-angle neutron scattering, where the particle concentration is also extracted directly from the experimental curves. The two sets of data reveal similar structural evolution with concentration at the interface and in the bulk and an increase in the degree of ordering with the particle size.
Collapse
Affiliation(s)
- Marguerite Léang
- Laboratoire Léon Brillouin , CEA-CNRS, Université Paris-Saclay, CEA-Saclay , 91191 Gif sur Yvette Cedex , France
- Laboratoire F.A.S.T. , Université Paris-Sud, CNRS, Université Paris-Saclay , F-91405 Orsay , France
| | - Didier Lairez
- Laboratoire Léon Brillouin , CEA-CNRS, Université Paris-Saclay, CEA-Saclay , 91191 Gif sur Yvette Cedex , France
- Laboratoire des Solides Irradiés , Ecole Polytechnique, CEA-CNRS, Université Paris-Saclay , 91128 Palaiseau Cedex , France
| | - Fabrice Cousin
- Laboratoire Léon Brillouin , CEA-CNRS, Université Paris-Saclay, CEA-Saclay , 91191 Gif sur Yvette Cedex , France
| | | | - Ludovic Pauchard
- Laboratoire F.A.S.T. , Université Paris-Sud, CNRS, Université Paris-Saclay , F-91405 Orsay , France
| | - Lay-Theng Lee
- Laboratoire Léon Brillouin , CEA-CNRS, Université Paris-Saclay, CEA-Saclay , 91191 Gif sur Yvette Cedex , France
| |
Collapse
|
21
|
Koga S, Inasawa S. Packing structures and formation of cracks in particulate films obtained by drying colloid–polymer suspensions. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2018.11.066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
22
|
Abstract
Polygonal desiccation crack patterns are commonly observed in natural systems. Despite their quotidian nature, it is unclear whether similar crack patterns which span orders of magnitude in length scales share the same underlying physics. In thin films, the characteristic length of polygonal cracks is known to monotonically increase with the film thickness; however, existing theories that consider the mechanical, thermodynamic, hydrodynamic, and statistical properties of cracking often lead to contradictory predictions. Here we experimentally investigate polygonal cracks in drying suspensions of micron-sized particles by varying film thickness, boundary adhesion, packing fraction, and solvent. Although polygonal cracks were observed in most systems above a critical film thickness, in cornstarch-water mixtures, multiscale crack patterns were observed due to two distinct desiccation mechanisms. Large-scale, primary polygons initially form due to capillary-induced film shrinkage, whereas small-scale, secondary polygons appear later due to the deswelling of the hygroscopic particles. In addition, we find that the characteristic area of the polygonal cracks, A_{p}, obeys a universal power law, A_{p}=αh^{4/3}, where h is the film thickness. By quantitatively linking α with the material properties during crack formation, we provide a robust framework for understanding multiscale polygonal crack patterns from microscopic to geologic scales.
Collapse
Affiliation(s)
- Xiaolei Ma
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
| | - Janna Lowensohn
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
| | - Justin C Burton
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
| |
Collapse
|
23
|
Abstract
This work investigates the role of surface parameters such as the nanoscale roughness, topography, and skewness of smooth and rough Si surfaces in the shape of patterns left by evaporating colloidal droplets of spherical polystyrene particles. The droplet contact angle, colloidal deposition pattern, crack density, and rim growth velocities are experimentally evaluated for varying roughness. The contact angle and rim growth rate are found to be more for rough surfaces in comparison to smooth ones. Roughness also helps in reducing stress in the drying droplets, thereby impeding the process of crack formation as exemplified by the experimental results. The altered Derjaguin-Landau-Verwey-Overbeek (DLVO) interactions emerging from the contribution of nanoscale roughness are theoretically evaluated for each differently rough substrate-particle combination. The forces have been calculated by considering large- and small-scale roughness parameters of the experimental surfaces. The experimental findings have been duly corroborated by theoretical estimates. Finally, it is observed that the skewness of the surface and the small-scale asperity radius bear a correlation with the DLVO forces and subsequently with the ring deposit pattern. The present understanding of the influence of surface fluctuations on evaporative self-assembly would enable one to choose the right topographic surface for particular applications.
Collapse
Affiliation(s)
- Deepa Lohani
- Department of Physics , Indian Institute of Technology Ropar , Nangal Road , Rupnagar , Punjab 140001 , India
| | - Subhendu Sarkar
- Department of Physics , Indian Institute of Technology Ropar , Nangal Road , Rupnagar , Punjab 140001 , India
| |
Collapse
|
24
|
Yang B, Smith ND, Johannes A, Burghammer M, Smith MI. Shear bands and the evolving microstructure in a drying colloidal film studied with scanning µ-SAXS. Sci Rep 2018; 8:12979. [PMID: 30154430 DOI: 10.1038/s41598-018-31405-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 08/14/2018] [Indexed: 11/09/2022] Open
Abstract
Shear localisation in thin bands is an important process involved in the plastic deformation of materials subject to stress. This process is often sensitive to the sample microstructure (amorphous/crystalline). Here we show using the scanning µ-SAXS technique, how these different microstructures influence the plastic deformations in a drying colloidal film. In crystalline samples, the presence of an ordering transition at the compaction front was directly identified through the development of a six-fold symmetry in the scattering pattern in 20 wt% samples. It is shown that plastic deformations in individual groups of particles during the compaction process can be tracked and measured in real time. Higher concentration suspensions were found to result in amorphous structures. The transition between crystalline and amorphous microstructures with initial particle concentration was also found to correlate with the appearance of shear bands. Through 2D spatial mapping of the local film structure, the presence of shear bands in the films was directly related to the microscale spatial variations in strain magnitude and compression direction. Our measurements also showed that shear bands lead to a reduction in the local particle volume fraction ~1–2%, indicating significant dilatancy.
Collapse
|
25
|
Kobayashi N, Sakai S, Sasaki Y, Kubo M, Tsukada T, Sugioka KI, Takami S, Adschiri T. Crack Formation in Polymer Nanocomposite Thin Films Containing Surface-Modified Nanoparticles during Solution Casting. Journal of Chemical Engineering of Japan 2018. [DOI: 10.1252/jcej.17we323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Shinji Sakai
- Department of Chemical Engineering, Tohoku University
| | - Yudai Sasaki
- Department of Chemical Engineering, Tohoku University
| | - Masaki Kubo
- Department of Chemical Engineering, Tohoku University
| | - Takao Tsukada
- Department of Chemical Engineering, Tohoku University
| | - Ken-ichi Sugioka
- Department of Mechanical Systems Engineering, Toyama Prefectural University
| | - Seiichi Takami
- Department of Materials Process Engineering, Nagoya University
| | | |
Collapse
|
26
|
Abe K, Inasawa S. A quantitative study of enhanced drying flux from a narrow liquid–air interface of colloidal suspensions during directional drying. Phys Chem Chem Phys 2018; 20:8935-8942. [DOI: 10.1039/c7cp07668a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Drying flux changes by the drying interfacial area of a colloidal suspension that affects the formation kinetics of particulate films.
Collapse
Affiliation(s)
- Kohei Abe
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology
- Tokyo 184-8588
- Japan
| | - Susumu Inasawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology
- Tokyo 184-8588
- Japan
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology
- Tokyo 184-8588
| |
Collapse
|
27
|
Abstract
Shrinkage cracks are observed in many materials, particularly in paintings where great interest lies in deducing quantitative information on the material with the aim of proposing authentication methods. We present experimental measurements on the crack opening induced by the drying of colloidal layers and compare these results to the case of a pictorial layer. We propose a simple model to predict the crack width as a function of the thickness of the drying layer, based on the balance between the drying stress buildup and the shear frictional stress with the substrate. Key parameters of the model include the mechanical properties that are measured experimentally using micro-indentation testing. A good agreement between theory and experimental data for both colloidal layers and the real painting is found. These results, by comparing the shrinkage cracks in model layers and in pictorial layers, validate the method based on the use of colloidal systems to simulate and to reproduce drying cracks in paintings.
Collapse
Affiliation(s)
- Marguerite Léang
- Laboratoire F.A.S.T, UMR 7608 CNRS - Univ. Paris-Sud, Université Paris-Saclay, 91405, Orsay CEDEX, France.
| | | | | | | |
Collapse
|
28
|
Schneider M, Maurath J, Fischer SB, Weiß M, Willenbacher N, Koos E. Suppressing Crack Formation in Particulate Systems by Utilizing Capillary Forces. ACS Appl Mater Interfaces 2017; 9:11095-11105. [PMID: 28263554 PMCID: PMC5375100 DOI: 10.1021/acsami.6b13624] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Cracks, formed during the drying of particulate films, can reduce the effectiveness or even render products useless. We present a novel, generic approach to suppress crack formation in thin films made from hard particle suspensions, which are otherwise highly susceptible to cracking, using the capillary force between particles present when a trace amount of an immiscible liquid is added to a suspension. This secondary liquid preserves the particle cohesion, modifying the structure and increasing the drying rate. Crack-free films can be produced at thicknesses much greater than the critical cracking thickness for a suspension without capillary interactions, and even persists after sintering. This capillary suspension strategy is applicable to a broad range of materials, including suspensions of metals, semiconductive and ceramic oxides, or glassy polymeric particles, and can be easily implemented in many industrial processes since it is based on well-established unit operations. Promising fields of application include ceramic foils and printed electronic devices.
Collapse
Affiliation(s)
- Monica Schneider
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Straße 3, 76131 Karlsruhe, Germany
| | - Johannes Maurath
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Straße 3, 76131 Karlsruhe, Germany
| | - Steffen B. Fischer
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Straße 3, 76131 Karlsruhe, Germany
- Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200f, 3001 Leuven, Belgium
| | - Moritz Weiß
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Straße 3, 76131 Karlsruhe, Germany
- Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200f, 3001 Leuven, Belgium
| | - Norbert Willenbacher
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Straße 3, 76131 Karlsruhe, Germany
| | - Erin Koos
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Straße 3, 76131 Karlsruhe, Germany
- Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200f, 3001 Leuven, Belgium
- Corresponding Author,
| |
Collapse
|
29
|
Guo L, Ren Y, Kong LY, Chim WK, Chiam SY. Ordered fragmentation of oxide thin films at submicron scale. Nat Commun 2016; 7:13148. [PMID: 27748456 DOI: 10.1038/ncomms13148] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 09/07/2016] [Indexed: 11/08/2022] Open
Abstract
Crack formation is typically undesirable as it represents mechanical failure that compromises strength and integrity. Recently, there have also been numerous attempts to control crack formation in materials with the aim to prevent or isolate crack propagation. In this work, we utilize fragmentation, at submicron and nanometre scales, to create ordered metal oxide film coatings. We introduce a simple method to create modified films using electroplating on a prepatterned substrate. The modified films undergo preferential fragmentation at locations defined by the initial structures on the substrate, yielding ordered structures. In thicker films, some randomness in the characteristic sizes of the fragments is introduced due to competition between crack propagation and crack creation. The method presented allows patterning of metal oxide films over relatively large areas by controlling the fragmentation process. We demonstrate use of the method to fabricate high-performance electrochromic structures, yielding good coloration contrast and high coloration efficiency. Fracture and related processes are typically considered detrimental, but have also attracted interest in more constructive roles. Here authors demonstrate ordered fragmentation at submicron scales of a metal oxide/hydroxide thin film by introducing preferential sites for fracture on the underlying substrate.
Collapse
|
30
|
Yang B, Sharp JS, Smith MI. The interplay of crack hopping, delamination and interface failure in drying nanoparticle films. Sci Rep 2016; 6:32296. [PMID: 27558989 DOI: 10.1038/srep32296] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 08/04/2016] [Indexed: 11/19/2022] Open
Abstract
Films formed through the drying of nanoparticle suspensions release the build-up of strain through a variety of different mechanisms including shear banding, crack formation and delamination. Here we show that important connections exist between these different phenomena: delamination depends on the dynamics of crack hopping, which in turn is influenced by the presence of shear bands. We also show that delamination does not occur uniformly across the film. As cracks hop they locally initiate the delamination of the film which warps with a timescale much longer than that associated with the hopping of cracks. The motion of a small region of the delamination front, where the shear component of interfacial crack propagation is believed to be enhanced, results in the deposition of a complex zig-zag pattern on the supporting substrate.
Collapse
|
31
|
Inasawa S, Oshimi Y, Kamiya H. Formation kinetics of particulate films in directional drying of a colloidal suspension. Soft Matter 2016; 12:6851-6857. [PMID: 27471046 DOI: 10.1039/c6sm01524g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We observed the kinetics of formation of colloidal films through directional drying with a pinned drying interface. The volume fraction of particles accumulated at the pinned drying interface increased in two stages: it rapidly increased in the initial stage of drying and then slowly increased. The final filling factor of the dried films decreased with increasing drying flux. We found a threshold drying flux for the formation of colloidal films below which uneven films are formed at the drying interface. This threshold flux is well explained by the competition between transport of particles by flow and transport by diffusion. We also found a minimum thickness for the formation of a packed layer of particles. The formation kinetics of a packed layer of particles due to drying was discussed.
Collapse
Affiliation(s)
- S Inasawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan. and Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan
| | - Y Oshimi
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan.
| | - H Kamiya
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan. and Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan
| |
Collapse
|
32
|
Boulogne F, Kong YL, Nunes JK, Stone HA. Effect of the Polydispersity of a Colloidal Drop on Drying Induced Stress as Measured by the Buckling of a Floating Sheet. Phys Rev Lett 2016; 116:238001. [PMID: 27341259 DOI: 10.1103/physrevlett.116.238001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Indexed: 06/06/2023]
Abstract
We study the stress developed during the drying of a colloidal drop of silica nanoparticles. In particular, we use the wrinkling instability of a thin floating sheet to measure the net stress applied by the deposit on the substrate and we focus on the effect of the particle polydispersity. In the case of a bidisperse suspension, we show that a small number of large particles substantially decreases the expected stress, which we interpret as the formation of lower hydrodynamic resistance paths in the porous material. As colloidal suspensions are usually polydisperse, we show for different average particle sizes that the stress is effectively dominated by the larger particles of the distribution and not by the average particle size.
Collapse
Affiliation(s)
- François Boulogne
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Yong Lin Kong
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Janine K Nunes
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| |
Collapse
|
33
|
Abstract
Colloidal dispersions are known to display a fascinating network of cracks on drying. We probe the fracture mechanics of free-standing films of aqueous polymer-particle dispersions. Thin films of the dispersion are cast between a pair of plain steel wires and allowed to dry under ambient conditions. The strain induced on the particle network during drying is relieved by cracking. The stress which causes the films to crack has been calculated by measuring the deflection of the wires. The critical cracking stress varied inversely to the two-thirds' power of the film thickness. We also measure the velocity of the tip of a moving crack. The motion of a crack has been modeled as a competition between the release of the elastic energy stored in the particle network, the increase in surface energy as a result of the growth of a crack, the rate of viscous dissipation of the interstitial fluid and the kinetic energy associated with a moving crack. There is fair agreement between the measured crack velocities and predictions.
Collapse
Affiliation(s)
- Rajarshi Sengupta
- Department of Chemical Engineering, Indian Institute of Technology Powai, Mumbai, India.
| | | |
Collapse
|
34
|
Liu T, Luo H, Ma J, Xie W, Wang Y, Jing G. Surface roughness induced cracks of the deposition film from drying colloidal suspension. Eur Phys J E Soft Matter 2016; 39:24. [PMID: 26920527 DOI: 10.1140/epje/i2016-16024-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Accepted: 09/25/2015] [Indexed: 06/05/2023]
Abstract
We investigate crack formation in deposition films from drying colloidal suspension drops, by varying the roughness and texture of the substrate. The experimental results indicate that the crack number or crack spacing presents a general dependence on the substrate roughness, despite the orientation of the substrate textures. Interestingly, the crack spacing decreases with the increase of the roughness. Two possible mechanisms are proposed to understand the dependence of the cracks on roughness. Firstly, the concentration reduction of the drying suspension due to collecting colloidal particles from the substrate textures decreases the crack spacing. Secondly, stress concentration resulting from the defects (the notches in textures) in the dried deposition enhances crack formation. However, a quantitative estimation by the calculation of the stress concentrating factors reveals that the notch of the substrate textures dominates crack variation. The results here bring forth a practical method for controlling the crack orientation and suppression, and a potential application to crack-free coatings, films and paintings during the drying of complex fluids.
Collapse
Affiliation(s)
- Tingting Liu
- School of Physics, Northwest University, 710069, Xi'an, China
| | - Hao Luo
- School of Physics, Northwest University, 710069, Xi'an, China
| | - Jun Ma
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Weiguang Xie
- Siyuan Laboratory, Department of Physics, Jinan University, Guangzhou, 510632, Guangdong, China
| | - Yan Wang
- Beijing Aeronautical Science & Technology Research Institute of COMAC, 102211, Beijing>, China
| | - Guangyin Jing
- School of Physics, Northwest University, 710069, Xi'an, China.
- National Key Laboratory and Incubation Base of Photoelectric Technology and Functional Materials, Northwest University, 710069, Xian, China.
| |
Collapse
|
35
|
Abstract
In directionally dried colloidal dispersions regular bands can appear behind the drying front, inclined at ±45° to the drying line. Although these features have been noted to share visual similarities with shear bands in metal, no physical mechanism for their formation has ever been suggested, until very recently. Here, through microscopy of silica and polystyrene dispersions, dried in Hele-Shaw cells, we demonstrate that the bands are indeed associated with local shear strains. We further show how the bands form, that they scale with the thickness of the drying layer, and that they are eliminated by the addition of salt to the drying dispersions. Finally, we reveal the origins of these bands in the compressive forces associated with drying, and show how they affect the optical properties (birefringence) of colloidal films and coatings.
Collapse
Affiliation(s)
| | - Lucas Goehring
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany
| |
Collapse
|
36
|
Abstract
Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles.
Collapse
Affiliation(s)
- Jin Young Kim
- Soft Matter Physics Laboratory, School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea
| | - Kun Cho
- Soft Matter Physics Laboratory, School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea
| | - Seul-A Ryu
- Soft Matter Physics Laboratory, School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea
| | - So Youn Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Byung Mook Weon
- Soft Matter Physics Laboratory, School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea
| |
Collapse
|
37
|
Abstract
We investigate the dynamics of solidification of a charged colloidal dispersion using an original microfluidic technique referred to as micropervaporation. This technique exploits pervaporation within a microfluidic channel to extract the solvent of a dilute colloidal dispersion. Pervaporation concentrates the colloids in a controlled way up to the tip of the channel until a wet solid made of closely packed colloids grows and invades the microfluidic channel. For the charged dispersion under study, we however evidence a liquid to solid transition (LST) preceding the formation of the solid, owing to the presence of long-range electrostatic interactions. This LST is associated with the nucleation and growth of domains confined in the channel. These domains are then compacted anisotropically up to forming a wet solid of closely packed colloids. This solid then invades the whole channel as in directional drying with a growth rate which depends on the microfluidic geometry. In the final steps of the solidification, we observed the occurrence of cracks and shear bands, the delamination of the wet solid from the channel walls, and its invasion by a receding air front. Interestingly, this air front follows specific patterns within the solid which reveal different microscopic colloidal organizations.
Collapse
Affiliation(s)
- Nadia Ziane
- CNRS, Solvay, LOF, UMR 5258, Univ. Bordeaux, F-33600 Pessac, France
| | | |
Collapse
|
38
|
Ghosh UU, Chakraborty M, Bhandari AB, Chakraborty S, DasGupta S. Effect of Surface Wettability on Crack Dynamics and Morphology of Colloidal Films. Langmuir 2015; 31:6001-6010. [PMID: 25973978 DOI: 10.1021/acs.langmuir.5b00690] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The effect of surface wettability on the dynamics of crack formation and their characteristics are examined during the drying of aqueous colloidal droplets (1 μL volume) containing nanoparticles (53 nm mean particle diameter, 1 w/w %). Thin colloidal films, formed during drying, rupture as a result of the evaporation-induced capillary pressure and exhibit microscopic cracks. The crack initiation and propagation velocity as well as the number of cracks are experimentally evaluated for substrates of varying wettability and correlated to their wetting nature. Atomic force and scanning electron microscopy are used to examine the region in the proximity of the crack including the particle arrangements near the fracture zone. The altered substrate-particle Derjaguin-Landau-Verwey-Overbeek (DLVO) interactions, as a consequence of the changed wettability, are theoretically evaluated and found to be consistent with the experimental observations. The resistance of the film to cracking is found to depend significantly on the substrate surface energy and quantified by the critical stress intensity factor, evaluated by analyzing images obtained from confocal microscopy. The results indicate the possibility of controlling crack dynamics and morphology by tuning the substrate wettability.
Collapse
Affiliation(s)
- Udita Uday Ghosh
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Monojit Chakraborty
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Aditya Bikram Bhandari
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Suman Chakraborty
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Sunando DasGupta
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| |
Collapse
|
39
|
Abstract
Drying suspensions of colloidal nanoparticles exhibit a variety of interesting strain release mechanisms during film formation. These result in the selection of characteristic length scales during failure processes such as cracking and subsequent delamination. A wide range of materials (e.g., bulk metallic glasses) release strain through plastic deformations which occur in a narrow band of material known as a shear band. Here we show that drying colloidal films also exhibit shear banding. Bands are observed to form a small distance behind the drying front and then to propagate rapidly at ∼45° to the direction of drying. It is shown that the spacing of the bands depends on salt concentration and the evaporation rate of the colloidal suspension. These combined observations suggest that there is a critical shear rate (related to the film yield stress) which controls the ratio of bandwidth to band spacing. Local deformations were measured in the early stages of drying using fluorescent tracer particles. The measurements were used to show that the existence of shear bands is linked to the compaction of particles perpendicular to the drying front. The spacing of shear bands was also found to be strongly correlated with the characteristic length scale of the compaction process. These combined studies elucidate the role of plastic deformation during pattern formation in drying films of colloidal nanoparticles.
Collapse
Affiliation(s)
- Bin Yang
- †School of Physics and Astronomy and ‡Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - James S Sharp
- †School of Physics and Astronomy and ‡Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Michael I Smith
- †School of Physics and Astronomy and ‡Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| |
Collapse
|
40
|
Mino Y, Watanabe S, Miyahara MT. In situ observation of meniscus shape deformation with colloidal stripe pattern formation in convective self-assembly. Langmuir 2015; 31:4121-4128. [PMID: 25831052 DOI: 10.1021/acs.langmuir.5b00467] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Vertical convective self-assembly is capable of fabricating stripe-patterned structures of colloidal particles with well-ordered periodicity. To unveil the mechanism of the stripe pattern formation, in the present study, we focus on the meniscus shape and conduct in situ observations of shape deformation associated with particulate line evolution. The results reveal that the meniscus is elongated downward in a concave fashion toward the substrate in accordance with solvent evaporation, while the concave deformation is accelerated by solvent flow, resulting in the rupture of the liquid film at the thinnest point of the meniscus. The meniscus rupture triggers the meniscus to slide off from the particulate line, followed by the propagation of the sliding motion of the three-phase contact line, resulting in the formation of stripe spacing.
Collapse
Affiliation(s)
- Yasushi Mino
- Department of Chemical Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Satoshi Watanabe
- Department of Chemical Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Minoru T Miyahara
- Department of Chemical Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
| |
Collapse
|
41
|
Kappert EJ, Pavlenko D, Malzbender J, Nijmeijer A, Benes NE, Tsai PA. Formation and prevention of fractures in sol-gel-derived thin films. Soft Matter 2015; 11:882-888. [PMID: 25466584 DOI: 10.1039/c4sm02085e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sol-gel-derived thin films play an important role as the functional coatings for various applications that require crack-free films to fully function. However, the fast drying process of a standard sol-gel coating often induces mechanical stresses, which may fracture the thin films. An experimental study on the crack formation in sol-gel-derived silica and organosilica ultrathin (submicron) films is presented. The relationships among the crack density, inter-crack spacing, and film thickness were investigated by combining direct micrograph analysis with spectroscopic ellipsometry. It is found that silica thin films are more prone to fracturing than organosilica films and have a critical film thickness of 300 nm, above which the film fractures. In contrast, the organosilica films can be formed without cracks in the experimentally explored regime of film thickness up to at least 1250 nm. These results confirm that ultrathin organosilica coatings are a robust silica substitute for a wide range of applications.
Collapse
Affiliation(s)
- Emiel J Kappert
- Inorganic Membranes Group, University of Twente, MESA+ Institute for Nanotechnology and Faculty of Science and Technology, PO Box 217, 7500 AE Enschede, The Netherlands.
| | | | | | | | | | | |
Collapse
|
42
|
Giorgiutti-Dauphiné F, Pauchard L. Elapsed time for crack formation during drying. Eur Phys J E Soft Matter 2014; 37:39. [PMID: 24853634 DOI: 10.1140/epje/i2014-14039-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 04/18/2014] [Accepted: 04/28/2014] [Indexed: 06/03/2023]
Abstract
The drying of colloidal films usually leads to mechanical instabilities that affect the uniformity of the final deposit. The resulting patterns are the signature of the mechanical stress, and reveal the way the system consolidates. We report experimental results on the crack patterns induced by the drying of sessile drops of concentrated dispersions. Crack patterns exhibit a well-defined spatial order, and a regular temporal periodicity. In addition, the onset of cracking occurs after a well-defined elapsed time that depends on the mechanical properties of the gel, and on the drying kinetics. The estimation of the time elapsed before cracks form is related to the elastic properties of the material. This is supported by quantitative measurements using indentation testing and by a simple scaling law derived from poro-elastic theory.
Collapse
Affiliation(s)
- F Giorgiutti-Dauphiné
- CNRS, F-91405, Lab FAST, Bat 502, Campus Univ, Univ Paris-Sud, F-91405, Orsay, France
| | | |
Collapse
|
43
|
Mailer AG, Clegg PS. Cracking in films of titanium dioxide nanoparticles with varying interaction strength. J Colloid Interface Sci 2014; 417:317-24. [DOI: 10.1016/j.jcis.2013.11.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 11/30/2022]
|
44
|
Abstract
Large-scale highly ordered microchannels were spontaneously and rapidly created by simply drying the colloidal nanoparticle suspension on a rigid substrate. Interestingly, free evaporation of colloidal suspension yielded radially aligned microchannels, while constrained evaporation that was rendered by the use of confined geometries composed of either two nearly parallel plates or a slide placed perpendicular to a rigid substrate imparted the formation of periodic arrays of parallel microchannels in a controllable manner. The microchannels were formed as a result of the competition between stress relaxation due to crack opening that ruptured the film and stress increase due to the loss of solvent. Quite intriguingly, these patterned microchannels can be exploited as templates to craft well-ordered metallic stripes. This facile and scalable approach may offer a new paradigm of producing microscopic patterns over large areas with unprecedented regularity at low cost that can serve as scaffolds for use in microelectronics and microfluidic-based biochips, among other areas.
Collapse
Affiliation(s)
- Wei Han
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | | | | |
Collapse
|
45
|
Abstract
When thin films of colloidal fluids are dried, a range of transitions are observed and the final film profile is found to depend on the processes that occur during the drying step. This article describes the drying process, initially concentrating on the various transitions. Particles are seen to initially consolidate at the edge of a drying droplet, the so-called coffee-ring effect. Flow is seen to be from the centre of the drop towards the edge and a front of close-packed particles passes horizontally across the film. Just behind the particle front the now solid film often displays cracks and finally the film is observed to de-wet. These various transitions are explained, with particular reference to the capillary pressure which forms in the solidified region of the film. The reasons for cracking in thin films is explored as well as various methods to minimize its effect. Methods to obtain stratified coatings through a single application are considered for a one-dimensional drying problem and this is then extended to two-dimensional films. Different evaporative models are described, including the physical reason for enhanced evaporation at the edge of droplets. The various scenarios when evaporation is found to be uniform across a drying film are then explained. Finally different experimental techniques for examining the drying step are mentioned and the article ends with suggested areas that warrant further study.
Collapse
Affiliation(s)
- Alexander F Routh
- BP Institute and Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
| |
Collapse
|
46
|
Abstract
A new method utilizing subsequent depositions of thin crack-free nanoparticle layers is demonstrated to avoid the formation of cracks within silica nanoparticle films. Using this method, films can be assembled with thicknesses exceeding the critical cracking values. Explanation of this observed phenomenon is hypothesized to mainly arise from chemical bond formation between neighboring silica nanoparticles. Application of this method for fabricating crack-free functional structures is demonstrated by producing crack-free Bragg reflectors that exhibit structural color.
Collapse
Affiliation(s)
- Jacob H Prosser
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | |
Collapse
|