The synthesis of poly(vinyl cinnamates) with light-induced shape fixity properties

Poly(vinyl cinnamates) (PVCi) with different degrees of substitution (DS) are synthesized by esterifying hydroxyl of poly(vinyl alcohol) (PVA) with carboxyl of p-chloro-substituted cinnamic acid. The grafted polymer has photosensitive property and presents photocrosslinking due to the photodimerization between pendant cinnamate groups, which affords PVCi sample photo induced shape fixity properties. That is to say PVCi sample having original shape could be deformed into a temporary shape under extra load followed by irradiating it under ultraviolet (UV) light of 360 nm. What interesting is the shape fixity has strong relationship with DS. Unfortunately, the deformed sample cannot recover its original shape under UV light of 254 nm. The reason behind the macroscopic shape change has been studied. And the effect of DS on the grafted polymer structure and properties has been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and UV spectra.