Chemical modification strategies for the control of graphene localization in PS/PMMA blend

This work concerns the nanoparticles localization control in a PMMA/PS polymer blend. In this article, a complete study was made on the poly(methylmethacrylate)/polystyrene/graphene (PMMA/PS/graphene) polymer blend nanocomposites performed by a melt-blending process at PMMA/PS equal proportion (50/50). Graphene nanoparticles were modified via different chemical modification strategies such as Hummers’ oxidation (GOxH), hydrazine reduction (GOxH-r2) and copolymer functionalization by a “grafting onto” method. The evolution of graphene nanoparticles morphology, chemical structure during the melt-blending process were investigated to explain their final localization. Considering GOxH nanoparticles, the in-situ reduction during the process was proved by Raman spectroscopy, FTIR and XRD. The stability of the copolymer grafting was also confirmed after melt-compounding by Py-GC/MS. The predicted localization by thermodynamics was compared to the real localization determined by STEM images. Functionalized graphene (GOxN-PMMA, GOxH-PMMA, GOxH-r2-PMMA, GOxH-r2-PMMA-r1) showed a transfer from PS to PMMA, whereas non-functionalized nanoparticles (G, GOxH, GOxH-r2) remain in PS. Graphene migration mechanisms and polymer blend microstructures were also investigated. Graphene nanoparticles interaction with polymer matrices and their impact on viscosity was studied by rheology to assess the final microstructure of the polymer blend nanocomposites.