The Influence of Amphoteric Terpolymerization of Poly (N-Isopropylacrylamide) in the Optimization of the Phase Separation Temperatures

Abstract

AbstractThe aim of this study is to fabricate an ampholyte thermo-responsive terpolymers and explore the influence of ampholyte on the phase separation temperatures in different pH solutions. The fabrication of the ampholyte thermo-responsive terpolymers was achieved by terpolymerization of N-isopropylacrylamide (NIPAAm), DIVA (5, 10, and 15 mol.%), and acrylic acid (AA) 10 mol.%. The preparation of the cationic monomer from vanillin was achieved in a facile reaction named 2-((diisopropylamino) methyl)-4-formyl-6-methoxyphenyl acrylate (DIVA). The chemical structures of the monomers and terpolymers were evaluated successfully by 1H, 13C NMR, and FTIR. The average molecular weight and dispersity of the terpolymers were characterized using gel permeation chromatography (GPC); the glass transition temperature, crystallinity, and morphology were characterized using DSC, XRD, and SEM, respectively. The hydrophilic/hydrophobic properties of the fabricated terpolymers, at different pH conditions, were evaluated using contact angle measurements. The lower critical solution temperature (LCST) for all samples was measured using UV–vis spectrophotometer. Moreover, the LCST was tested using different Hofmeister salts in kosmotropic and chaotropic conditions. The findings of this study can be utilized in the bio-separation of biological molecules, as well as drug delivery applications. Graphical Abstract