A Novel Shape Memory Poly(ε-caprolactone) Network via UV-Triggered Thiol-Ene Reaction

A facile method to prepare shape memory polymers crosslinked by SiO2 is described. A series of biodegradable shape memory networks were obtained through thiol-ene reaction triggered by UV irradiation between surface-thiol-modified SiO2 nanoparticles and end-acrylate poly (epsilon-caprolactone) (PCL). The highly selective thiol-ene reaction ensured a uniform distribution of PCL chains between crosslinkers, contributing well-defined network architecture with enhanced mechanical and shape-memory properties. Thiol-functionalized silica nanoparticle was characterized by using FTIR and XPS analysis, and H-1 NMR spectra was used to confirm the successful modification of terminal hydroxyl group of PCL diol. Surface-modified silica particles were found well dispersible in acrylate-capped PCL supported by SEM. Thermal and crystalline behaviors of the obtained polymers were analyzed by DSC and XRD, and DMA measurement proved good mechanical property. The shape memory behavior and tensile strength was somewhat tunable by the length of PCL. Acceptably, sample SiO2-SMP2k presented 99% recovery ratio and 97% shape fixity, and its relatively high tensile strength showed an attractive potential for biomedical application. Finally, a possible molecular mechanism accounting for the shape memory property was illustrated. (C) 2017 Wiley Periodicals, Inc.