Preparation of ureido group bearing polymers and their upper critical solution temperature in water

Abstract

ABSTRACT Poly(2‐ureidoethylmethacrylate) (PUEM n ) was synthesized via reversible addition‐fragmentation chain transfer (RAFT) radical polymerization and following polymer reaction. We prepared two PUEM n samples with different degrees of polymerization ( n = 100 and 49). The polymers exhibited upper critical solution temperature (UCST) in phosphate‐buffered saline (PBS) solution. The phase separation temperature ( T p ) in PBS can be controlled ranging from 17 to 55 °C by changing molecular weight of the polymer, polymer concentration, and adding NaCl concentration. The polymers in PBS formed coacervate drops by liquid–liquid phase separations below T p . Results of the dielectric relaxation measurement, the hydration number per monomeric unit was 5 above T p . Based on a fluorescence study, the polymer formed slightly hydrophobic environments below T p . The liquid–liquid phase separation was occurred presumably because of weak hydrophobic interactions and intermolecularly hydrogen bonding interactions between the pendant ureido groups. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54 , 2845–2854