Synthesis and Shape Memory Properties of POSS-Capped Poly(ethylene oxide) Telechelics

Polyhedral oligomeric silsesquioxane (POSS)-capped poly(ethylene oxide) (PEO) telechelics were synthesized via click chemistry approach between azidopropylheptaphenyl-POSS and alknyl-capped PEO. In these telechelics, POSS cages aggregated into microdomains via POSS-POSS interaction and dispersed in the continuous PEO matrix, which was observed by transmission electron microscope (TEM). Rheological measurements showed that values of loss modulus were lower than that of storage loss in the range of angular frequency from 0.01 to 100 rad/s (1 rad/s=\dfrac 1 2\textπ \rmHz), indicating the formation of physical crosslinking network in POSS-PEO-POSS telechelics. The as-formed physical cross-linking sites endowed POSS-capped PEO telechelics with excellent thermal-induced shape recovery properties. Shape recovery rate was quite dependent on POSS content in the telechelics. The higher POSS content, the faster shape recovery rate. Moreover, the formation of physical crosslinking sites and hydrophilic features of PEO resulted in formation of hydrogels in water. These hydrogels displayed high swelling ratios and the swelling ratios increased with PEO lengths. More importantly, these hydrogels exhibited aqueously induced shape memory properties. This study prompted an innovative strategy to form physical crosslinking hydrogels via POSS-POSS interactions. The excellent thermally and aqueously induced shape memory properties make POSS-capped PEO telechelics promising as special biomedical devices.