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Chemical modification impact of graphene or graphite in conductive nanocomposite morphology control

Abstract : Carbon fillers are used for nanocomposite application in order to improve mechanical, thermal and electrical properties of polymers [1,2,3]. The last decade, graphene attracted much attention thanks to its 2D structure, high aspect ratio and high surface area. These intrinsic properties made it one of the most promising filler for the development of high added-value polymer nanocomposites. However, as graphene nanoparticles are difficult to disperse in polymer matrices, they must be incorporated in high amounts in order to create a percolation network and to obtain high electrical conductivities. Chemical modification is one of the solutions to improve the dispersion of graphene. Moreover, by controlling the graphene chemical modification to it is possible to orient its localization in an immiscible polymer blend. The present study is focusing first on the chemical modification influence of graphene and graphite on their structure (exfoliation, new covalent bonds). TGA, FTIR and Py-GC/MS characterization proved the chemical modification. XRD showed the structure modification with the intercalation of oxygenated groups and confirmed the exfoliation. Raman spectroscopy revealed high defect concentration due to the strong oxidation and formation of sp3 carbon. Then, these modified graphene and graphite were dispersed in a co-continuous PMMA/PS polymer blend. Due to the immiscibility of PMMA and PS polymers, an interface is formed during the melt blending. The aim is to allow the localization of the graphene platelets at the continuous interface by their surface modification. By placing graphene platelets at the interface, the percolation threshold is decreased [4]. Moreover, this localization at the interface is facilitated by the high exfoliation degree that tends to improve the flexibility of graphene particles. To reach the interface localization, graphene was first oxidized and then functionalized with a copolymer of methyl methacrylate and hydroxyethyl methacrylate (P(MMA-co-HEMA)). Then, functionalized graphene was dispersed in the PS matrix by solvent casting. This master batch was mixed by melt blending with the PMMA matrix. Due to the better affinity with PMMA, the functionalized graphene migrates to the interface during the melt process. AFM, SEM allowed to identify the localization of the functionalized graphene and graphite in polymer blends. Finally, a performant electrical material can be elaborated with lower amounts of graphene for uses in energy storage or aeronautic.
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Submitted on : Wednesday, December 8, 2021 - 4:34:24 PM
Last modification on : Friday, December 10, 2021 - 3:06:03 AM

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  • HAL Id : hal-03471091, version 1

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Thibaut Lalire. Chemical modification impact of graphene or graphite in conductive nanocomposite morphology control. Balard Chemistry Conferences - Materials for health, energy & environment, Jun 2021, Montpellier, France. ⟨hal-03471091⟩

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