Soft bacterial polyester-based shape memory nanocomposites featuring reconfigurable nanostructure

In this work, a novel soft shape memory polymer nanocomposite derived from a bacterial medium-chain-length polyhydroxyalkanoate, poly(3-hydroxyoctanoate- co-3-hydroxyundecenoate) (PHOU), used to form a covalent network grafted with polyhedral oligomeric silsesquioxane (POSS), a crystallizable inorganic-organic hybrid nanofiller, was prepared. The PHOU-POSS nanocomposite, PHOU-POSSw-net [w (= POSS content, wt %) = 0, 20, 25, 30, and 38], is a completely amorphous elastomer (w ≤ 20) or contains POSS nanocrystals embedded in the amorphous PHOU matrix (w ≥ 25). The hybrid nanostructure of PHOU-POSSw-net (w ≥ 25) is featured by its reconfigurability, based on aggregation and disaggregation of POSS covalently connected to the PHOU network, which enables excellent shape fixing and recovery. Furthermore, it exhibits soft and elastomeric mechanical properties even in the fixed state. Taking advantage of the shape memory ability as well as the softness in the fixed state, we demonstrate microscale dynamic surface topography of PHOU-POSSw-net.