A novel multi-functional model thermoset and PDA-coated PU nanocomposite based on graphene and an amphiphilic block copolymer

The need for multi-functional biomaterials has driven researchers towards more complex multi-component structures with tailor-made surface modifications. In this research, thermoset polyurethanes (tPUs) of PCLy-PEG(x)-PCLy, with variable block lengths, and graphene were developed and further surface-modified by Polydopamine (PDA) to improve cell adhesion. The viscoelastic and thermal properties of the tPUs were studied by DMA and DSC. The results proved the increased crystallization of the soft segments as the length of PCLy and PEG(x) blocks increased. The stress-strain results indicate the tPU nanocomposites possess high-elastic modulus (38.46-96.17 MPa), and lower elongation (132.6%-375.9%) compared to thermoplastic PU nanocomposites. The tPU specimens proved to have very high shape recovery ratios (88.07%-94.93%). PDA surface deposition led to an increase in surface roughness and a change in surface topography. The PDA-modified specimens showed significant improvement in protein adsorption and cell proliferation and also increased the hydrolytic degradation extent of the tPUs, proving the multi-functional role of the biomaterials.