Preparation of lipophilic graphene oxide derivates via a concise route and its mechanical reinforcement in thermoplastic polyurethane

A facile, effective and environmental friendly route was presented to prepare lipophilic graphene oxide (GO) derivates via the esterification reaction of the carboxylate salt of GO and 1-bromohexadecane in the presence of a phase-transfer reagent in water. The resultant long alkyl chains modified graphene oxide sheets (GO-HD) show the long-term and stable dispersion capability in many organic solvents. Successful grafting of long alkyl chains onto GO surfaces was confirmed through FTIR, XPS, TGA, UV-vis spectrum techniques. Moreover, we utilized the GO-HD as a reinforcing filler to prepare GO-HD/thermoplastic polyurethane (TPU) nanocomposites through solution casting method. The uniform distribution and good interfacial adhesion are expected for the GO-HD based nanocomposites due to the good compatibility between long alkyl chains of GO-HD fillers and TPU chains. Notably, tensile mechanical tests demonstrated that the GO-HD/TPU nanocomposites at low filler contents (≤2 wt%) exhibit higher modulus, ultimate tensile strength without compromising the intrinsic extensibility of TPU matrix as compared with the GO/TPU nanocomposites with same filler content. Further, in situ tensile-micro Raman spectroscopy tests were employed to monitor the load transfer process at a microscopic level, and revealed the improved load transfer efficiency in the GO-HD/TPU nanocomposites.