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Costinas C, Salagean CA, Cotet LC, Baia M, Todea M, Magyari K, Baia L. Insights into the Stability of Graphene Oxide Aqueous Dispersions. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4489. [PMID: 36558342 PMCID: PMC9785193 DOI: 10.3390/nano12244489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/06/2022] [Accepted: 12/14/2022] [Indexed: 06/17/2023]
Abstract
Understanding graphene oxide's stability (or lack thereof) in liquid solvents is critical for fine-tuning the material's characteristics and its potential involvement in future applications. In this work, through the use of structural and surface investigations, the alteration of the structural and edge-surface properties of 2D graphene oxide nanosheets was monitored over a period of eight weeks by involving DLS, zeta potential, XRD, XPS, Raman and FT-IR spectroscopy techniques. The samples were synthesized as an aqueous suspension by an original modified Marcano-Tour method centred on the sono-chemical exfoliation of graphite. Based on the acquired experimental results and the available literature, a phenomenological explanation of the two underlying mechanisms responsible for the meta-stability of graphene oxide aqueous dispersions is proposed. It is based on the cleavage of the carbon bonds in the first 3-4 weeks, while the bonding of oxygen functional groups on the carbon lattice occurs, and the transformation of epoxide and hydroxyl groups into adsorbed water molecules in a process driven by the availability of hydrogen in graphene oxide nanosheets.
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Affiliation(s)
- Codrut Costinas
- Faculty of Physics, Babeș-Bolyai University, M. Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania
| | - Catalin Alexandru Salagean
- Faculty of Physics, Babeș-Bolyai University, M. Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania
- Laboratory for Advanced Materials and Applied Technologies, Institute for Research, Development and Innovation in Applied Natural Sciences, Babeș-Bolyai University, Fântânele 30, RO-400294 Cluj-Napoca, Romania
| | - Liviu Cosmin Cotet
- Laboratory for Advanced Materials and Applied Technologies, Institute for Research, Development and Innovation in Applied Natural Sciences, Babeș-Bolyai University, Fântânele 30, RO-400294 Cluj-Napoca, Romania
- Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, Arany Janos 11, RO-400028 Cluj-Napoca, Romania
| | - Monica Baia
- Faculty of Physics, Babeș-Bolyai University, M. Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania
- Laboratory for Advanced Materials and Applied Technologies, Institute for Research, Development and Innovation in Applied Natural Sciences, Babeș-Bolyai University, Fântânele 30, RO-400294 Cluj-Napoca, Romania
| | - Milica Todea
- Nanostructured Materials and Bio-Nano-Interfaces Centre, Interdisciplinary Research Institute on Bio-Nano-Sciences, Babeș-Bolyai University, Treboniu Laurian 42, RO-400271 Cluj-Napoca, Romania
- Faculty of Medicine, Iuliu Hațieganu University of Medicine and Pharmacy, Victor Babeș 8, RO-400012 Cluj-Napoca, Romania
| | - Klara Magyari
- Nanostructured Materials and Bio-Nano-Interfaces Centre, Interdisciplinary Research Institute on Bio-Nano-Sciences, Babeș-Bolyai University, Treboniu Laurian 42, RO-400271 Cluj-Napoca, Romania
- Department of Applied and Environmental Chemistry, University of Szeged, Rerrich B. Sqr. 1, 6720 Szeged, Hungary
| | - Lucian Baia
- Faculty of Physics, Babeș-Bolyai University, M. Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania
- Laboratory for Advanced Materials and Applied Technologies, Institute for Research, Development and Innovation in Applied Natural Sciences, Babeș-Bolyai University, Fântânele 30, RO-400294 Cluj-Napoca, Romania
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Poly(Vinyl Chloride) Spheres Coated with Graphene Oxide Sheets: From Synthesis to Optical Properties and Their Applications as Flame-Retardant Agents. Polymers (Basel) 2021; 13:polym13040565. [PMID: 33672830 PMCID: PMC7917685 DOI: 10.3390/polym13040565] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/10/2021] [Accepted: 02/10/2021] [Indexed: 01/09/2023] Open
Abstract
A new method to obtain poly(vinyl chloride) (PVC) spheres, which consists of an interaction between commercial PVC grains and hexyl ethyl cellulose and lauroyl peroxide at a temperature of 60 °C, is reported. The addition of the graphene oxide (GO) sheets dispersed in dimethylformamide to the reaction mixture leads to the generation of composites made of PVC spheres coated with GO sheets. Scanning electron microscopy studies have demonstrated that this method allows for the transformation of PVC grains with sizes between 75 and 227 μm into spheres with sizes varying from 0.7 to 3.5 μm when the GO concentration in the PVC/GO composite mass increases from 0.5 to 5 wt.%. Our studies of Raman scattering and FTIR spectroscopy highlight a series of changes that indicate the appearance of ClCH=CH–, CH2=CCl–, and/or –CH=CCl– units as a result of PVC partial dehydrogenation. New –COO– and C–OH bonds on the GO sheet surfaces are induced during the preparation of PVC spheres coated with GO sheets. A photoluminescence (PL) band with a maximum at 325 nm is reported to characterize the PVC spheres. A PVC PL quenching process is demonstrated to be induced by the increase in the concentration of the GO sheets in the PVC/GO composite mass. The perspectives regarding the use of this composite as a flame-retardant material are also reported.
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Zhou H, Song Y. Fabrication of Silver Mesh/Grid and Its Applications in Electronics. ACS APPLIED MATERIALS & INTERFACES 2021; 13:3493-3511. [PMID: 33440929 DOI: 10.1021/acsami.0c18518] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
With the development of flexible electronics, researchers have endeavored to improve the characteristics of the commonly used indium tin oxide such as brittleness, poor mechanical or chemical stability, and scarcity. Currently, many alternative materials have been considered such as conductive polymers, graphene, carbon nanotubes, metallic nanoparticles (NPs), nanowires (NWs), or nanofibers. Among them, silver (Ag) mesh/grid NPs or NWs have been considered as an excellent substitute due to the good transmittance, excellent electrical conductivity, outstanding mechanical robustness, and cost competitiveness. So far, much effort has been devoted to the fabrication of Ag mesh/grid, and many methods such as printing technology, self-assembly, electrospun, hot-pressing, and atomic layer deposition have been reported. Here printing technologies include jet printing, gravure printing, screen printing, nanoimprint lithography, microcontact printing, and flexographic printing. The solution-based self-assembly usually combines with coating, template, or mask assistance. This review summarizes the characteristics of these fabrication methods for the Ag mesh/grid with its related applications in electronics. Then the prospect and challenges of the fabrication methods are discussed, and the new preparation approaches and applications of the Ag mesh/grid are highlighted, which will be of significance for the applications in electronics such as transparent conducting electrodes, organic light-emitting diode, energy harvester, strain sensor, cells, etc.
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Affiliation(s)
- Haihua Zhou
- Key Laboratory of Green Printing, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing Engineering Research Center of Nanomaterials for Green Printing Technology, Beijing National Laboratory for Molecular Sciences, Beijing 100190, China
| | - Yanlin Song
- Key Laboratory of Green Printing, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing Engineering Research Center of Nanomaterials for Green Printing Technology, Beijing National Laboratory for Molecular Sciences, Beijing 100190, China
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