A Facile Method for the Preparation of Hydrophilic-Hydrophobic Functional Thermo-pH Responsive Terpolymers Based on Poly (NIPAAm-co-DMAA-co-DMAMVA) and Post-polymerization

A new monomer has been synthesized on the basis of vanillin. This compound has the advantage of having a tertiary amine group, which makes it one of the pH-responsive monomers. Moreover, the active aldehyde group facilitates the additional reaction modification like the post-polymerization through Schiff reaction by reaction with primary amine compounds like amino acids. The name of the compound is 2-((dimethylamino)methyl)-4-formyl-6-methoxyphenyl acrylate (DMAMVA). The compounds have been evaluated by 1H, 13C NMR, and FTIR. A new series of polymers has been fabricated by free radical polymerization of N,N-dimethylacrylamide, and 5, 10, and 15 mol% of DMAMVA with N-isopropylacrylamide to produce the dual-responsive thermo-pH polymers. They were reacted with amino acid by post-polymerization according to Schiff base click reaction. All polymers have been investigated chemically in addition to physical characterizations e.g., molecular weight by GPC, glass transition temperature by DSC, chemical decomposition TGA, and morphological by SEM. The study was focused on the determination of phase transition temperatures and LCST of the polymer solution; it has been done using two methods one by UV–VIS-spectroscopy as turbidity test, while the other new technology by micro-DSC. More applications for these polymers will be applied in bio-separation and biotechnology in our future work.