Fabrication of photo-active trans-3-(4-pyridyl)acrylic acid modified chitosan.

Photo-active trans-3-(4-pyridyl)acrylic acid (PYA) modified chitosan (CSPA) was synthesized with different functionalization degrees and extensively examined using Fourier transform infrared spectra (FTIR), 1H and 13C nuclear magnetic resonance (NMR) in order to elucidate the chemical structure of the modified biopolymer. The modified CSPA with various substitution degrees were casted in form of thin membranes and cross-linked under photo-chemical condition by exposure to ultra-violet light via [2π+2π] cycloaddition reaction of the incorporated PYA units. The photo-induced reaction was examined using UV-vis light spectra and the cross-linked hydrogel were investigated using both XRD and scanning electron microscope (SEM). Also, the mechanical properties of the hydrogel membranes were studied by measuring the variations of both tensile strength and elongation against corss-linking densities.