Bio-based tough hyperbranched polyurethane–graphene oxide nanocomposites as advanced shape memory materials

Abstract

A fast and simple approach for the large scale fabrication of highly flexible castor oil-modified hyperbranched polyurethane (HPU)–graphene oxide (GO) nanocomposites with high toughness is reported. Three different wt% (0.5, 1 and 2) of GO are incorporated into a HPU matrix to prepare uniformly dispersed GO-based nanocomposites. The performance studies show a tremendous enhancement of the toughness (2540 to 6807 MJ m⁻³) as well as the increment of tensile strength (7 to 16 MPa), elongation at break (695 to 810%) and scratch hardness (5 to 6.5 kg) on the formation of the nanocomposites with 2 wt% GO. The Halpin–Tsai model suggests the 3D random distribution of GO in the HPU matrix. Thermal properties such as thermostability, melting point, enthalpy, degree of crystallinity and glass transition temperature (T_g) etc. of the nanocomposites are correlated with their shape recovery (∼99.5%) and shape fixity (∼90%) behaviour. Thus, HPU–GO nanocomposites have the potential to be used as advanced thermo-responsive shape memory materials.