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 group of thermoset polyurethane (tPU) nanocomposites were synthesized. Poly(ε-caprolactone) (PCL 2000 ), Poly (tetramethylene glycol) (PTMG 2000 ), and different architecture and compositions of PCL and PTMG were used as diols. Cellulose nanowhisker (CNW), with 1.0 wt% content, was used to cross-link the prepolymers and to produce high-modulus specimens for high shape memory performance. The analyses of crystallization showed that thermal stability of the PTMG and PCL crystallites decreases upon block copolymerization, blending and incorporation of the block copolymer into the blend (about 10\(℃\) decrease). Cross-linking of the prepolymers using CNW has also reduced the crystallites’ thermal stability to a large extent (about 50\(℃\) decrease). The results of the Dynamic Mechanical Thermal Analysis (DMTA) also showed that the thermoset PUs have a large elastic modulus at above room temperature (higher than 10 MPa) and very small tanδ height (below 0.15), which was attributed to its semi-crystalline nature and presence of CNW with high elastic modulus (110–220 GPa). The thermomechanical behavior of the tPUs proved to be ideal for acquiring high shape memory performance. The tPUs have also proved to be highly biocompatible.