Synthesis of N-vinylcaprolactam copolymers with N-vinylformamide and physicochemical properties of their aqueous solutions

Water-soluble thermoprecipitable copolymers of N-vinylcaprolactam and N-vin ylformamide were synthesized by free-radical polymerization, and the reacti vity ratios of these comonomers were determined. The acidic hydrolysis of v inylcaprolactam-vinylformamide copolymers was carried out to produce vinylc aprolactam-vinylamine copolymers. The solubility of the resulting copolymer s in various solvents was studied. It was shown that the copolymers have a controllable LCST, depending on their composition. When 20 to 80 mol % of v inylformamide units were introduced into the macromolecular chain of poly(v inylcaprolactam), the temperature of thermoprecipitation increased from 33 to 62 degrees C, while in the case of vinylamine units, the temperature of thermoprecipitation increased from 35 to 95 degrees C. The vinylcaprolactam -vinylamine copolymers also possess polyelectrolyte properties.