Poly(N-isopropylacrylamide-co-2-((diethylamino)methyl)-4-methylphenyl acrylate) thermo-ph responsive copolymer: trend in the lower critical solution temperature optimization of Poly (N-isopropyylacrylamide)

A new series of thermo-pH responsive polymers based on N-isopropylacrylamide and new cationic monomer has been synthesized from p-cresol in two facile steps and named by 2-((diethylamino)methyl)-4-methylphenyl acrylate), and abbreviated by (DEAMPA). It has been investigated by 1H NMR, 13C NMR, and FT IR. Three copolymers have been fabricated with three different molar concentrations of DEAMPA 5, 10, and 20 mol% using the free radical polymerization technique in solution. The copolymers have been chemically evaluated by 1H NMR and FT IR as well. Moreover, the physical characterizations were also investigated; the molecular weights and dispersity by GPC, the glass transition temperature by DSC, the change in the mass by decomposition using TGA, the degree of crystallinity by X-ray diffractions, and the morphological features by SEM. The change in the lower critical solution temperature and the phase separation of polymers solutions were measured by turbidity test as the change in transmittance with temperature with concerning the change in pH and using UV–VIS spectroscopy. The new cationic thermo-pH responsive copolymer will be used in the preparation of sensors, and dual responsive hydrogel.