Abstract
The present study emphasizes the fabrication of thermal and pH-responsive photo-cross-linked polymers and hydrogel thin films. N-isopropylacrylamide was used as a thermal responsive monomer, while a new pH-responsive monomer was synthesized based on vanillin 2-((dimethylamino)methyl)-4-formyl-6-methoxyphenyl acrylate (DMAMVA). The photo-cross-linker (DMIA) and adhesion promotor (DMITAAc) have been prepared. All compounds were investigated by 1H NMR, 13C NMR, and FTIR. Terpolymers of 10, 15, and 20 mol% DMAMVA and 10 mol% of DMIA with N-isopropylacrylamide were fabricated. The chemical structures were investigated, and the molecular weights were determined by gel permeation chromatography GPC. Moreover, the glass transition temperatures were also recorded by differential scanning calorimeter DSC. The lower critical solution temperatures of polymers were determined by turbidity tests using UV-Vis spectroscopy. The polymer solution of 20 mol% sample was spin-coated over the gold to form hydrogel thin film within photo-cross-linking by the UV lamp. The film thickness was determined by the SPR-OW technique using Kretschmann configuration. The swelling was recorded and the transition temperature of hydrogel was determined as the change in volume degree of swelling and refractive index with the change in temperature. The dual responsive functional photo-cross-linked polymers and hydrogel thin films have significant importance in the grafting of some biological molecules.