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Xian W, Zhan YS, Maiti A, Saab AP, Li Y. Filled Elastomers: Mechanistic and Physics-Driven Modeling and Applications as Smart Materials. Polymers (Basel) 2024; 16:1387. [PMID: 38794580 PMCID: PMC11125212 DOI: 10.3390/polym16101387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Elastomers are made of chain-like molecules to form networks that can sustain large deformation. Rubbers are thermosetting elastomers that are obtained from irreversible curing reactions. Curing reactions create permanent bonds between the molecular chains. On the other hand, thermoplastic elastomers do not need curing reactions. Incorporation of appropriated filler particles, as has been practiced for decades, can significantly enhance mechanical properties of elastomers. However, there are fundamental questions about polymer matrix composites (PMCs) that still elude complete understanding. This is because the macroscopic properties of PMCs depend not only on the overall volume fraction (ϕ) of the filler particles, but also on their spatial distribution (i.e., primary, secondary, and tertiary structure). This work aims at reviewing how the mechanical properties of PMCs are related to the microstructure of filler particles and to the interaction between filler particles and polymer matrices. Overall, soft rubbery matrices dictate the elasticity/hyperelasticity of the PMCs while the reinforcement involves polymer-particle interactions that can significantly influence the mechanical properties of the polymer matrix interface. For ϕ values higher than a threshold, percolation of the filler particles can lead to significant reinforcement. While viscoelastic behavior may be attributed to the soft rubbery component, inelastic behaviors like the Mullins and Payne effects are highly correlated to the microstructures of the polymer matrix and the filler particles, as well as that of the polymer-particle interface. Additionally, the incorporation of specific filler particles within intelligently designed polymer systems has been shown to yield a variety of functional and responsive materials, commonly termed smart materials. We review three types of smart PMCs, i.e., magnetoelastic (M-), shape-memory (SM-), and self-healing (SH-) PMCs, and discuss the constitutive models for these smart materials.
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Affiliation(s)
- Weikang Xian
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (W.X.); (Y.-S.Z.)
| | - You-Shu Zhan
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (W.X.); (Y.-S.Z.)
| | - Amitesh Maiti
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.M.); (A.P.S.)
| | - Andrew P. Saab
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.M.); (A.P.S.)
| | - Ying Li
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (W.X.); (Y.-S.Z.)
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2
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Micheletti C, Chubak I, Orlandini E, Smrek J. Topology-Based Detection and Tracking of Deadlocks Reveal Aging of Active Ring Melts. ACS Macro Lett 2024:124-129. [PMID: 38198592 PMCID: PMC10883035 DOI: 10.1021/acsmacrolett.3c00567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Connecting the viscoelastic behavior of stressed ring melts to the various forms of entanglement that can emerge in such systems is still an open challenge. Here, we consider active ring melts, where stress is generated internally, and introduce a topology-based method to detect and track consequential forms of ring entanglements, namely, deadlocks. We demonstrate that, as stress accumulates, more and more rings are co-opted in a growing web of deadlocks that entrap many other rings by threading, bringing the system to a standstill. The method ought to help the study of topological aging in more general polymer contexts.
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Affiliation(s)
- Cristian Micheletti
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
| | - Iurii Chubak
- Sorbonne Université CNRS, Physico-Chimie des électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
| | - Enzo Orlandini
- Università degli studi di Padova, Dipartimento di Fisica "G. Galilei", Via Marzolo 8, I-35100 Padova, Italy
| | - Jan Smrek
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
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3
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Ninarello A, Ruiz-Franco J, Zaccarelli E. Auxetic polymer networks: The role of crosslinking, density, and disorder. J Chem Phys 2023; 159:234902. [PMID: 38108485 DOI: 10.1063/5.0178409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 11/24/2023] [Indexed: 12/19/2023] Open
Abstract
Low-crosslinked polymer networks have recently been found to behave auxetically when subjected to small tensions, that is, their Poisson's ratio ν becomes negative. In addition, for specific state points, numerical simulations revealed that diamond-like networks reach the limit of mechanical stability, exhibiting values of ν = -1, a condition that we define as hyper-auxeticity. This behavior is interesting per se for its consequences in materials science but is also appealing for fundamental physics because the mechanical instability is accompanied by evidence of criticality. In this work, we deepen our understanding of this phenomenon by performing a large set of equilibrium and stress-strain simulations in combination with phenomenological elasticity theory. The two approaches are found to be in good agreement, confirming the above results. We also extend our investigations to disordered polymer networks and find that the hyper-auxetic behavior also holds in this case, still manifesting a similar critical-like behavior as in the diamond one. Finally, we highlight the role of the number density, which is found to be a relevant control parameter determining the elastic properties of the system. The validity of the results under disordered conditions paves the way for an experimental investigation of this phenomenon in real systems, such as hydrogels.
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Affiliation(s)
- Andrea Ninarello
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - José Ruiz-Franco
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Emanuela Zaccarelli
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
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4
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Mizuno T, Hayashi M, Takahashi R. Unusual Stress Upturn in Elastomers Prepared Using Macro Cross-Linkers with Multiple Vinyl Side Groups. Macromol Rapid Commun 2023; 44:e2200936. [PMID: 36840973 DOI: 10.1002/marc.202200936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/06/2023] [Indexed: 02/27/2023]
Abstract
In this study, the unique tensile properties of acrylate elastomers prepared using macro cross-linker polymers with multiple vinyl side groups are analyzed. For the preparation of the macro cross-linker, poly(ethyl acrylate) copolymers bearing hydroxy functional groups are synthesized, followed by the hydroxy-isocyanate reaction with 2-isocyanatoethyl acrylate. Subsequently, the elastomers samples are prepared by UV polymerization of ethyl acrylate in the presence of the macro cross-linkers. The tensile properties of the elastomers in the small elongation region are similar to those of typical elastomers prepared using divinyl cross-linkers, whereas the stress upturn in the large elongation region is considerably different. The stress upturn varies based on the fraction of vinyl side groups in the macro cross-linkers, whereas stress in the small elongation region remains unchanged. These properties are analyzed using various theoretical models. The results reveal that there is artificial inhomogeneity in the cross-link density for samples prepared by the macro cross-linkers, where the short poly(ethyl acrylate) strands inside the macro cross-linker limit the overall chain stretchability. On the whole, this study demonstrates a new method for tuning elastomer properties, especially at large deformation.
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Affiliation(s)
- Tatsuya Mizuno
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho Showa-ku, Nagoya-city, Aichi, 466-8555, Japan
| | - Mikihiro Hayashi
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho Showa-ku, Nagoya-city, Aichi, 466-8555, Japan
| | - Rintaro Takahashi
- Department of Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya-city, Aichi, 464-8603, Japan
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5
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Sorichetti V, Ninarello A, Ruiz-Franco J, Hugouvieux V, Zaccarelli E, Micheletti C, Kob W, Rovigatti L. Structure and elasticity of model disordered, polydisperse, and defect-free polymer networks. J Chem Phys 2023; 158:074905. [PMID: 36813705 DOI: 10.1063/5.0134271] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The elasticity of disordered and polydisperse polymer networks is a fundamental problem of soft matter physics that is still open. Here, we self-assemble polymer networks via simulations of a mixture of bivalent and tri- or tetravalent patchy particles, which result in an exponential strand length distribution analogous to that of experimental randomly cross-linked systems. After assembly, the network connectivity and topology are frozen and the resulting system is characterized. We find that the fractal structure of the network depends on the number density at which the assembly has been carried out, but that systems with the same mean valence and same assembly density have the same structural properties. Moreover, we compute the long-time limit of the mean-squared displacement, also known as the (squared) localization length, of the cross-links and of the middle monomers of the strands, showing that the dynamics of long strands is well described by the tube model. Finally, we find a relation connecting these two localization lengths at high density and connect the cross-link localization length to the shear modulus of the system.
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Affiliation(s)
- Valerio Sorichetti
- Laboratoire Charles Coulomb (L2C), Univ. Montpellier, CNRS, F-34095 Montpellier, France
| | | | | | | | | | - Cristian Micheletti
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy
| | - Walter Kob
- Laboratoire Charles Coulomb (L2C), Univ. Montpellier, CNRS, F-34095 Montpellier, France
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6
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Lloyd EM, Vakil JR, Yao Y, Sottos NR, Craig SL. Covalent Mechanochemistry and Contemporary Polymer Network Chemistry: A Marriage in the Making. J Am Chem Soc 2023; 145:751-768. [PMID: 36599076 DOI: 10.1021/jacs.2c09623] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Over the past 20 years, the field of polymer mechanochemistry has amassed a toolbox of mechanophores that translate mechanical energy into a variety of functional responses ranging from color change to small-molecule release. These productive chemical changes typically occur at the length scale of a few covalent bonds (Å) but require large energy inputs and strains on the micro-to-macro scale in order to achieve even low levels of mechanophore activation. The minimal activation hinders the translation of the available chemical responses into materials and device applications. The mechanophore activation challenge inspires core questions at yet another length scale of chemical control, namely: What are the molecular-scale features of a polymeric material that determine the extent of mechanophore activation? Further, how do we marry advances in the chemistry of polymer networks with the chemistry of mechanophores to create stress-responsive materials that are well suited for an intended application? In this Perspective, we speculate as to the potential match between covalent polymer mechanochemistry and recent advances in polymer network chemistry, specifically, topologically controlled networks and the hierarchical material responses enabled by multi-network architectures and mechanically interlocked polymers. Both fundamental and applied opportunities unique to the union of these two fields are discussed.
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Affiliation(s)
- Evan M Lloyd
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States
| | - Jafer R Vakil
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States
| | - Yunxin Yao
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States
| | - Nancy R Sottos
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States.,Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois61801, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States
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7
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Clarke BR, Kim H, Ilton M, Watkins JJ, Crosby AJ, Tew GN. The Impact of Polymerization Chemistry on the Mechanical Properties of Poly(dimethylsiloxane) Bottlebrush Elastomers. Macromolecules 2022. [PMID: 37502106 PMCID: PMC10373355 DOI: 10.1021/acs.macromol.2c01332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We compare the low-strain mechanical properties of bottlebrush elastomers (BBEs) synthesized using ring-opening metathesis and free radical polymerization. Through comparison of experimentally measured elastic moduli and those predicted by an ideal, affine model, we evaluate the efficiency of our networks in forming stress-supporting strands. This comparison allowed us to develop a structural efficiency ratio that facilitates the prediction of mechanical properties relative to polymerization chemistry (e.g., softer BBEs when polymerizing under dilute conditions). This work highlights the impact that polymerization chemistry has on the structural efficiency ratio and the resultant mechanical properties of BBEs with identical side chains, providing another "knob" by which to control polymer network properties.
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Affiliation(s)
- Brandon R. Clarke
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Hyemin Kim
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Mark Ilton
- Department of Physics, Harvey Mudd College, Claremont, California 91711, United States
| | - James J. Watkins
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Alfred J. Crosby
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Gregory N. Tew
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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8
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Furuya T, Koga T. Effects of Primary Structure of Reactive Polymers on Network Structure and Mechanical Properties of Gels. MACROMOL THEOR SIMUL 2022. [DOI: 10.1002/mats.202200044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tsutomu Furuya
- Department of Polymer Chemistry Graduate School of Engineering Kyoto University Katsura Kyoto 615‐8510 Japan
| | - Tsuyoshi Koga
- Department of Polymer Chemistry Graduate School of Engineering Kyoto University Katsura Kyoto 615‐8510 Japan
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9
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Sobarzo PA, Jessop IA, Pérez Y, Hauyon RA, Velázquez‐Tundidor MV, Medina J, González A, García LE, González‐Henríquez CM, Coll D, Ortiz PA, Tundidor‐Camba A, Terraza CA. Synthesis of dimethyl‐ and diphenylsilane‐based oligo(azine)s: Thermal, optical, electronic, and morphological properties. J Appl Polym Sci 2022. [DOI: 10.1002/app.52911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Patricio A. Sobarzo
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
| | - Ignacio A. Jessop
- Laboratory of Organic and Polymeric Materials, Department of Chemistry Universidad de Tarapacá Arica Chile
| | - Yasmín Pérez
- Laboratory of Organic and Polymeric Materials, Department of Chemistry Universidad de Tarapacá Arica Chile
| | - René A. Hauyon
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
| | - María V. Velázquez‐Tundidor
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
| | - Jean Medina
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
| | - Alexis González
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
| | - Luis E. García
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
| | - Carmen M. González‐Henríquez
- Laboratory of Nanotechnology and Advanced Materials (LNnMA), Chemistry Department Universidad Tecnológica Metropolitana Santiago Chile
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación (PIDi) Universidad Tecnológica Metropolitana Santiago Chile
| | - Deysma Coll
- Centro de Nanotecnología Aplicada, Facultad de Ciencias Universidad Mayor Santiago Chile
- Núcleo de Química y Bioquímica, Facultad de Estudios Interdisciplinarios Universidad Mayor Santiago Chile
| | - Pablo A. Ortiz
- Centro de Nanotecnología Aplicada, Facultad de Ciencias Universidad Mayor Santiago Chile
- Núcleo de Química y Bioquímica, Facultad de Estudios Interdisciplinarios Universidad Mayor Santiago Chile
| | - Alain Tundidor‐Camba
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
- UC Energy Research Center Pontificia Universidad Católica de Chile Santiago Chile
| | - Claudio A. Terraza
- Research Laboratory for Organic Polymers (RLOP), Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Santiago Chile
- UC Energy Research Center Pontificia Universidad Católica de Chile Santiago Chile
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10
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Isogai T, Hayashi M. Critical Effects of Branch Numbers at the Cross-Link Point on the Relaxation Behaviors of Transesterification Vitrimers. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00560] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Taketo Isogai
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Mikihiro Hayashi
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
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11
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Rovigatti L, Sciortino F. Designing Enhanced Entropy Binding in Single-Chain Nanoparticles. PHYSICAL REVIEW LETTERS 2022; 129:047801. [PMID: 35939033 DOI: 10.1103/physrevlett.129.047801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 06/24/2022] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
Single-chain nanoparticles (SCNPs) are a new class of bio- and soft-matter polymeric objects in which a fraction of the monomers are able to form equivalently intra- or interpolymer bonds. Here we numerically show that a fully entropic gas-liquid phase separation can take place in SCNP systems. Control over the discontinuous (first-order) change-from a phase of independent diluted (fully-bonded) polymers to a phase in which polymers entropically bind to each other to form a (fully-bonded) polymer network-can be achieved by a judicious design of the patterns of reactive monomers along the polymer chain. Such a sensitivity arises from a delicate balance between the distinct entropic contributions controlling the binding.
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Affiliation(s)
- Lorenzo Rovigatti
- Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy and CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Francesco Sciortino
- Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
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12
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Tauber J, van der Gucht J, Dussi S. Stretchy and disordered: Toward understanding fracture in soft network materials via mesoscopic computer simulations. J Chem Phys 2022; 156:160901. [PMID: 35490006 DOI: 10.1063/5.0081316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Soft network materials exist in numerous forms ranging from polymer networks, such as elastomers, to fiber networks, such as collagen. In addition, in colloidal gels, an underlying network structure can be identified, and several metamaterials and textiles can be considered network materials as well. Many of these materials share a highly disordered microstructure and can undergo large deformations before damage becomes visible at the macroscopic level. Despite their widespread presence, we still lack a clear picture of how the network structure controls the fracture processes of these soft materials. In this Perspective, we will focus on progress and open questions concerning fracture at the mesoscopic scale, in which the network architecture is clearly resolved, but neither the material-specific atomistic features nor the macroscopic sample geometries are considered. We will describe concepts regarding the network elastic response that have been established in recent years and turn out to be pre-requisites to understand the fracture response. We will mostly consider simulation studies, where the influence of specific network features on the material mechanics can be cleanly assessed. Rather than focusing on specific systems, we will discuss future challenges that should be addressed to gain new fundamental insights that would be relevant across several examples of soft network materials.
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Affiliation(s)
- Justin Tauber
- Physical Chemistry and Soft Matter, Wageningen University, Wageningen, The Netherlands
| | - Jasper van der Gucht
- Physical Chemistry and Soft Matter, Wageningen University, Wageningen, The Netherlands
| | - Simone Dussi
- Physical Chemistry and Soft Matter, Wageningen University, Wageningen, The Netherlands
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13
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Chremos A, Horkay F, Douglas JF. Influence of network defects on the conformational structure of nanogel particles: From "closed compact" to "open fractal" nanogel particles. J Chem Phys 2022; 156:094903. [PMID: 35259888 PMCID: PMC8898093 DOI: 10.1063/5.0072274] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/30/2021] [Indexed: 12/11/2022] Open
Abstract
We propose an approach to generate a wide range of randomly branched polymeric structures to gain general insights into how polymer topology encodes a configurational structure in solution. Nanogel particles can take forms ranging from relatively symmetric sponge-like compact structures to relatively anisotropic open fractal structures observed in some nanogel clusters and in some self-associating polymers in solutions, such as aggrecan solutions under physiologically relevant conditions. We hypothesize that this broad "spectrum" of branched polymer structures derives from the degree of regularity of bonding in the network defining these structures. Accordingly, we systematically introduce bonding defects in an initially perfect network having a lattice structure in three and two topological dimensions corresponding to "sponge" and "sheet" structures, respectively. The introduction of bonding defects causes these "closed" and relatively compact nanogel particles to transform near a well-defined bond percolation threshold into "open" fractal objects with the inherent anisotropy of randomly branched polymers. Moreover, with increasing network decimation, the network structure of these polymers acquires other configurational properties similar to those of randomly branched polymers. In particular, the mass scaling of the radius of gyration and its eigenvalues, as well as hydrodynamic radius, intrinsic viscosity, and form factor for scattering, all undergo abrupt changes that accompany these topological transitions. Our findings support the idea that randomly branched polymers can be considered to be equivalent to perforated sheets from a "universality class" standpoint. We utilize our model to gain insight into scattering measurements made on aggrecan solutions.
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Affiliation(s)
- Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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14
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Hagita K, Murashima T. Molecular dynamics studies of entropic elasticity of condensed lattice networks connected with uniform functionality f = 4. SOFT MATTER 2022; 18:894-904. [PMID: 35013740 DOI: 10.1039/d1sm01641e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To study the linear region of entropic elasticity, we considered the simplest physical model possible and extracted the linear entropic regime by using the least squares fit and the minimum of the mean absolute error. With regard to the effect of the fluctuation of the strand length Ns, the strand length with fluctuation was set to a form proportional to (1.0 + C (R - 0.5)), where R is a uniform random number between 0 and 1 and C is the amplitude of fluctuation. This form enabled us to analytically calculate the fluctuation dependence of the elastic modulus G. To reveal the linear regions of entropic elasticity as a function of the strand length between neighboring nodes in lattices, molecular dynamics (MD) simulations of condensed lattice networks with harmonic bonds without the excluded volume interactions were performed. Stress-strain curves were estimated by performing uniaxial stretching MD simulations under periodic boundary conditions with a bead number density of 0.85. First, we used a diamond lattice with functionality f = 4. The linear region of the entropic elasticity was found to become larger with the increasing number of beads in a strand Ns. For Ns = 100, the linear region had a strain of up to 8 for a regular diamond lattice. We investigated the effect of strand length fluctuation on the diamond lattice, and we confirmed that the equilibrium shear modulus G increases as the obtained analytical prediction and the linear entropic region in the stress-strain curves becomes narrower with increasing fluctuation of Ns. To investigate the difference in network topology with the same functionality f and uniform strand length Ns, we performed MD simulations on regular networks of the BC-8 structure with f = 4 prepared from the ab initio DFT calculations of carbon at high pressure. We found that the elastic behavior depends on the network connectivity (i.e., topology). This indicates that the network topology plays an important role in the emergence of nonlinearity owing to the crossover from entropic to energetic elasticity.
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Affiliation(s)
- Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka 239-8686, Japan.
| | - Takahiro Murashima
- Department of Physics, Tohoku University, 6-3, Aramaki-aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
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15
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Ninarello A, Ruiz-Franco J, Zaccarelli E. Onset of criticality in hyper-auxetic polymer networks. Nat Commun 2022; 13:527. [PMID: 35082298 PMCID: PMC8791937 DOI: 10.1038/s41467-022-28026-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 12/21/2021] [Indexed: 11/08/2022] Open
Abstract
Against common sense, auxetic materials expand or contract perpendicularly when stretched or compressed, respectively, by uniaxial strain, being characterized by a negative Poisson's ratio ν. The amount of deformation in response to the applied force can be at most equal to the imposed one, so that ν = - 1 is the lowest bound for the mechanical stability of solids, a condition here defined as "hyper-auxeticity". In this work, we numerically show that ultra-low-crosslinked polymer networks under tension display hyper-auxetic behavior at a finite crosslinker concentration. At this point, the nearby mechanical instability triggers the onset of a critical-like transition between two states of different densities. This phenomenon displays similar features as well as important differences with respect to gas-liquid phase separation. Since our model is able to faithfully describe real-world hydrogels, the present results can be readily tested in laboratory experiments, paving the way to explore this unconventional phase behavior.
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Affiliation(s)
- Andrea Ninarello
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy
| | - José Ruiz-Franco
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy
| | - Emanuela Zaccarelli
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy.
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy.
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Tauber J, Rovigatti L, Dussi S, van der Gucht J. Sharing the Load: Stress Redistribution Governs Fracture of Polymer Double Networks. Macromolecules 2021; 54:8563-8574. [PMID: 34602652 PMCID: PMC8482750 DOI: 10.1021/acs.macromol.1c01275] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Indexed: 11/28/2022]
Abstract
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The stress response
of polymer double networks depends not only
on the properties of the constituent networks but also on the interactions
arising between them. Here, we demonstrate, via coarse-grained simulations,
that both their global stress response and their microscopic fracture
mechanics are governed by load sharing through these internetwork
interactions. By comparing our results with affine predictions, where
stress redistribution is by definition homogeneous, we show that stress
redistribution is highly inhomogeneous. In particular, the affine
prediction overestimates the fraction of broken chains by almost an
order of magnitude. Furthermore, homogeneous stress distribution predicts
a single fracture process, while in our simulations, fracture of sacrificial
chains takes place in two steps governed by load sharing within a
network and between networks, respectively. Our results thus provide
a detailed microscopic picture of how inhomogeneous stress redistribution
after rupture of chains governs the fracture of polymer double networks.
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Affiliation(s)
- Justin Tauber
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Lorenzo Rovigatti
- Dipartimento di Fisica, Sapienza-Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Simone Dussi
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Jasper van der Gucht
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
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Sorichetti V, Hugouvieux V, Kob W. Dynamics of Nanoparticles in Polydisperse Polymer Networks: from Free Diffusion to Hopping. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01394] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Valerio Sorichetti
- Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS, Université Paris-Saclay, F-91405 Orsay, France
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
- IATE, Université Montpellier, INRAE, Institut Agro, F-34060 Montpellier, France
| | - Virginie Hugouvieux
- IATE, Université Montpellier, INRAE, Institut Agro, F-34060 Montpellier, France
| | - Walter Kob
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
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