Synthesis of high-modulus thermoset PUs of PCL-PTMG/CNW biomaterials with different soft domain architecture and composition for high shape memory performance

In this research work, a series of thermoset polyurethane (tPU) nanocomposites and a thermoplastic PU (TPPU) were synthesized using semi-crystalline polyols. Poly(epsilon-caprolactone) (PCL), poly(tetramethylene glycol) (PTMG), and different architecture and compositions of PCL and PTMG were used as diols. PCL was used to synthesize a TPPU (PCL-TPPU) as the control specimen. Cellulose nanowhisker (CNW), with 1.0 wt% content, was used for synthesis of the tPU nanocomposites. The aim of this research was to investigate the impact of the thermosetting using CNWs and tuning crystallization of the polyols on the shape memory performance (SMP) of PUs. The analysis of the polyols' crystallization and crystallization of the soft segments in the PU structures was studied to evaluate the impact of structural changes on the SMP of the PUs. The results of the dynamic mechanical thermal analysis showed that the tPUs have a large elastic modulus (E') at temperatures around similar to 25-40 degrees C (similar to 10 MPa) and very small tan delta height (below 0.15), which was attributed to their thermoset nature and presence of CNW with high E ' value (similar to 110-220 GPa). The PCL-TPPU, as the control specimen, showed E ' in the range of 200-400 kPa. The PUs have also proved to be highly biocompatible. [GRAPHICS] .