Biobased and Biodegradable Shape Memory Polymers of Eucommia Ulmoides Gum and Polycaprolactone via Dynamic Vulcanization

Abstract

The shape memory polymers (SMPs) are intelligent and adaptive materials that can undergo shape recovery in response to external stimuli. The combination of functionality, adjustable properties, and renewability has endowed SMPs with burgeoning interest. The biobased and biodegradable SMPs were successfully prepared by incorporating natural Eucommia ulmoides gum (EUG) and polycaprolactone (PCL) as the constituents through dynamic vulcanization. The fine phase morphology of EUG/PCL SMPs was achieved through complete phase inversion and the establishment of good interfacial compatibility between the PCL and EUG phases, which positively influenced their mechanical and shape memory properties. The EUG/PCL SMPs demonstrated exceptional shape recovery properties, with a remarkable 97% shape recovery and 99% shape fixity. Moreover, the EUG/PCL SMPs also exhibited remarkable reprocessability, and the reprocessed EUG/PCL SMPs still showcased exceptional shape memory properties. The crystalline EUG functioned synergistically as a fixed phase alongside PCL, thereby effectively stabilizing the deformed shape. Specifically, the cross-linked and elastic EUG particles dispersed in PCL provided sufficient restoring force to drive the PCL molecular chains to recover their initial shape.