Fabrication of Smart Shape Memory Fluorosilicon Thermoplastic Vulcanizates: The Effect of Interfacial Compatibility and Tiny Crystals

To expand the application of shape memory materials in situations where elevated temperature and corrosion resistance are required, novel heat-triggered shape memory (HSM) fluorosilicon thermoplastic vulcanizates (TPVs) were designed via core-shell dynamic vulcanization. When the fluororubber (FKM)/silicone rubber (SR) ratio reached 1:1, excellent shape fixity (R-f similar to 96%) and shape recovery ratios (R-r similar to 98%) were achieved at the suitable switching transition temperature (T-trans) of 160 degrees C. The influence of core-shell structure on shape memory behavior mainly comes from the following aspects: the improvement of interfacial compatibility promoting stress delivery between polyvinylidene fluoride (PVDF) and SR/FKM phases in the shape fixing and shape recovery process and the reduced number-average rubber particle size caused by the appropriate interfacial compatibility facilitating the increasing of interface area, which improved the nucleation density and induced abundant tiny crystals in the blends. Additionally, the formation of core-shell structure also endowed the TPVs with improved mechanical properties.