Trends in the Phase Separation Temperature Optimization of a Functional and Thermo-pH Responsive Terpolymer of Poly (N-isopropylacrylamide-co-N-(2-(dimethylamino)ethyl) Acrylamide-co-vanillin Acrylate)

To optimize the phase separation temperature of poly (N-isopropylacrylamide) two monomers have been used to fabricate a series of three functional and thermo-pH terpolymers. N-(2-(dimethylamino)ethyl)acrylamide (DMAEAm) acts as a hydrophilic and pH-responsive monomer and 4-formyl-2-methoxyphenylacrylate or vanillin acrylate (VA) as hydrophobic and functional monomer both monomers have been synthesized in a one-step reaction. They were investigated by 1H, 13C NMR, and FTIR and demonstrated good agreement with their chemical structures. Dual responsive functional terpolymers have been fabricated in different molar ratios of (DMAEAm) (10, 15, and 20 mol%) with 10 mol% of VA; they have been investigated by chemical methods such as 1H, and FTIR as well. The physical characterization has also been achieved using GPC for molecular weight and molecular weight distributions, DSC for glass transition temperature. The vital point is studying the phase separation temperature or the lower critical solution temperature of the polymer solution, and the relative influence of DMAEAm and VA on transition temperature Tc of terpolymer solution; it has been recorded by turbidity test using UV–Vis-spectroscopy as the change of transmittance with temperature, on the other hand using micro-DSC of the polymer solution was tested. This optimization in the poly (NIPAAm) characterization encourages the application of the new terpolymer as a biosensor.