Preparation Of The Poly(Urethane-vinyl Imidazole)/Graphene Nano Composites

Graphene, a two-dimensional (2D) honeycomb lattice of carbon, has been considered as the thinnest and hardest material in the world. The remarkable properties of graphene, such as excellent electronic transport properties, superior mechanical properties, favorable thermal conductivity and high surface area, have attracted a great many research efforts in physics and chemistry, among which the polymer matrix nanocomposites is a hot research topic in these fields.In this paper, a series of polyurethane/graphene nano composites were successfully prepared and further investigated, with the main objective of realizing uniformed dispersion of graphene nano particles in polyurethane without agglomeration. First of all, the double bonds-terminated polyurethane(HPU) was synthesized and then poly(HPU/1-vinylimidazole) copolymers were fabricated by free radical polymerization. The results of FTIR showed that the Tg of soft segments of copolymers decreased when introducing 1-vinylimidazole. With content of 1-vinylimidazole increasing, the modulus, tensile strength and elongation at break of copolymers were all improved, according to the results of DMA and tensile testing.Secondly, single layer graphene was prepared from chemical reduction of GO. The distribution of graphene in DMF, 1-vinylimidazole and the mix-solution system was observed at room temperature respectively. The results showed that 1-vinylimidazole could improve the distribution of graphene in polyurethane matrix, demonstrating the positive effect of"π–π"interaction between the imidazole ring and graphene.Finally, the graphene was dispersed in 1-vinylimidazole to form a suspension, with which the HPU was initiated by BPO to undergoing situ copolymerization. The corresponding product, poly (urethane-co-vinylimidazole)/graphene nano composites, exhibited a certain improvement in tensile strength, modulus and thermal decomposition temperature. Moreover, the volume resistivity of poly(urethane-co-vinylimidazole)/graphene nano composites decreased by an order of magnitude after adding 0.5wt.% graphene, manifesting its significantl possibility to prepare conductive nano composites.