Environmental functional photo-cross-linked hydrogel bilayer thin films from vanillin (part 2): temperature-responsive layer A, functional, temperature and pH layer B

Abstract

Vanillin acrylate (VA) monomer was prepared and elucidated by 1H NMR 13C and FTIR. Three different mole ratios of smart functional photo-cross-linker polymers were synthesized by the copolymerization of N-isopropylacrylamide (5, 10 and 15 mol%) VA functional monomer and (2, 5 and 10 mol%) photo-cross-linkers. On the other hand, three different mole ratios (2, 5 and 10 mol%) of thermo-responsive photo-cross-linker polymers were prepared by copolymerization of (NIPAAm) and (DIMAAm). Polymers were characterized by 1HNMR, FTIR, UV, gel permeation chromatography (GPC) and differential scanning calorimetery (DSC). Lower critical solution temperatures (Tc) were determined by UV–Vis. Spectroscopy and micro-DSC. Hydrogel bilayer was formed by spin coating of polymer solution of poly(N-isopropylacrylamide-co-maleimide) layer A over gold with adhesion promoter, and then cross-linked by UV-irradiation. The next layer was formed by spin coating of polymer solution poly(N-isopropylacryamide-co-malimide-co-VA) layer B over layer A, and then cross-linked by UV-irradiation. The swelling properties and Tc were determined by SPR/OW. Our target is the formation of active centre for biological molecules using aldehyde group, which act as biosensor gel vessel. Further, the hydrogel bilayer will facilitate the target molecule to stay safely inside this gel vessel responsive to temperature and pH. New acrylate monomer from vanillin has been synthesized with aldehyde group to achieve both functionality and pH responsive. The copolymerization with NIPAAm and DMIAAm has done forming pH and temperature photo-cross-linked polymers. Hydrogel layer was built first with single then bilayer and both has characterized by SPR/OW. The effect of Temperature-responsive layer on the dual responsive one was demonstrated through the change lower critical solution temperature. In the nearest future, we will use this technique as biosensor hydrogel for biotechnology e.g., drug delivery and bio-separation.