The UCST phase transition of a dextran based copolymer in aqueous media with tunable thermoresponsive behavior

Abstract

A hydrogen bonded UCST polymer has been developed by grafting of methacrylamide and acrylic acid on dextran via free radical polymerization. By varying the methacrylamide concentration, four different grades of copolymers have been synthesized, which form H-bonds between acid and amide groups at low temperature. This makes the copolymer insoluble (forms aggregates) in water while becoming soluble beyond a certain temperature (T_CP) when the H-bonds collapse (aggregates break down), which is also evident from dynamic light scattering analysis. The effects of pH, monomer composition, and the concentration of the polymer and salt on the cloud point have been explored in detail.