The role of cellulose nanocrystals in the improvement of the shape-memory properties of castor oil-based segmented thermoplastic polyurethanes

The effect of the addition of cellulose nanocrystals on segmented thermoplastic polyurethane shape-memory properties was investigated. To this end, polyurethane bionanocomposites were synthesized by in situ polymerization, adding cellulose nanocrystals in the first step of polymerization and using components from renewable resources in polyurethane formulation. Thereby, microphase separated polyurethane/cellulose nanocrystal bionanocomposites were obtained, presenting two main transitions, soft and hard phase melting temperatures. Furthermore, it was observed that due to the addition of cellulose nanocrystals, hard phase crystallinity increased. Regarding thermally-activated shape-memory properties, a significant improvement was observed in the shape recovery values with the addition of cellulose nanocrystals, being these bionanocomposites good candidates to use in applications where shape-memory properties are required.