Fully Reversible Spherulitic Morphology in Cationically Photopolymerized DGEBA/PCL Shape-Memory Blends

Films with shape-memory properties were obtained after photocuring blends of diglycidyl ether of bisphenol A (DGEBA) with previously crystallized poly(e-caprolactone) (PCL). The effect of the epoxy photopolymerization on the semicrystalline PCL was studied, and transesterification reactions between epoxy and PCL were confirmed to occur in the amorphous regions of the DGEBA/PCL samples by Fourier transform infrared (FTIR) and gel content determination. Polarized light optical microscopy (PLOM) observations showed that because curing and transesterification reactions were confined to the amorphous regions of the sample, a spherulitic template was created with remarkable reversibility upon melting and recrystallization. To analyze the effect of this template on PCL crystallization, self-nucleation experiments were performed by differential scanning calorimetry (DSC). Within the spherulitic templates of photocured samples, in the amorphous regions, chains are confined near cross-linking points. The crystallin...