(751a) Reconfigurable Bacterial Polyester Nanocomposites Exhibiting Soft Shape Memory

Shape memory polymers (SMPs) with low stiffness in the “fixed” temporary shape (below the transition temperature, T_tr) as well as in the “relaxed” permanent shape (above T_tr) have tremendous potential in biomedical applications owing to better modulus match to soft tissues. However, for most existing SMPs, the conventional use of main-chain vitrification or crystallization to fix temporary shapes limits the opportunity to obtain soft “fixed” SMPs. In this paper, we report the preparation of novel soft SMP nanocomposites featuring reconfigurable nanostructures. The materials are derived from a bacterial medium-chain-length polyhydroxyalkanoate (mcl-PHA), poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) (PHOU), functionalized with polyhedral oligomeric silsesquioxane (POSS), a crystallizable nano-filler that is composed of an inorganic core and organic vertex groups. The PHOU–POSS nanocomposites exhibit excellent shape memory performance, and behave elastomerically both above and below T_tr. We attribute these properties to the ability of segregated POSS nano-domains to structurally reconfigure the amorphous PHOU network under different thermomechanical conditions. Owing to their biocompatibility, PHOU–POSS nanocomposites are promising materials for a variety of biomedical applications.