(530d) Self-Assembly and Mechanical Properties of Graphene/Acrylic Triblock Copolymer Gels

Polymeric gels are used in a wide variety of applications ranging from food materials to drug delivery to tissue engineering. Investigation of gel mechanical properties as a function of their microstructure is a significant research interest. This study presents the effect of graphene (or few-layer graphene) on the self-assembly and the mechanical properties of a thermoreversible gel consists of a physically cross-linked poly (methyl methacrylate)-poly (n-butyl acrylate)-poly (methyl methacrylate) [PMMA-PnBA-PMMA] triblock copolymer in 2-ethyl-1-hexanol, a midblock selective solvent. Graphene was obtained by sonicating exfoliated graphite in 2-ethyl-1-hexanol at various concentrations, 0.1-0.5 mg/mL. The level of exfoliation of graphene layers and the dimensions of individual graphene sheets were characterized using transmission electron microscopy. The dispersed graphene was then incorporated in a series of gels and the mechanical characterization of these gels was performed using a rheometer in oscillatory shear mode (small- and large-amplitude) and in compression mode. The effect of graphene on relaxation behavior of these gels was also studied. Small angle X-ray scattering (SAXS) was used to investigate the effect of graphene on the microstructure of these gels. The change in number of end blocks per junction zone and the average spacing between the junction zones were estimated from the SAXS data. The results indicate that the presence of graphene affects the self-assembly, gel points and the mechanical properties of the physical gels considered here.