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.

In this report, a tough elastomeric hyperbranched polyurethane/reduced graphene oxide (HPU/RGO) nanocomposite was fabricated by an in situ polymerization technique. Reduction of graphene oxide was carried out by a green sonochemical approach using the combined effect of sonication and Fe³⁺ ions in presence of Colocasia esculenta leaves aqueous extract. The reduction occurred only in 3 min, while 8 min was required without sonication. Prepared RGO and nanocomposites were characterized by different spectroscopic and analytical tools. The nanocomposite demonstrated excellent thermal stability and mechanical properties, such as tensile strength (27.8 MPa), tensile modulus (36.3 MPa) and toughness (116 MJ m⁻³). The nanocomposite also exhibited outstanding multi-stimuli responsive shape memory behaviour under direct sunlight, microwave (360 W) and heat energy (60 °C). The performance of the nanocomposite was dependent on the loading of RGO (0.5–2.5 wt%). Thus, these nanocomposites have tremendous potential to be used as advanced non-contact triggered smart materials for different applications, including biomedical.