Renewable lysine was cyclized to its corresponding alpha-amino-epsilon-caprolactam and then underwent the reaction with acryloyl chloride to harvest a 2-acrylamido-caprolactam (ACL) monomer. Subsequent reversible addition-fragmentation chain transfer copolymerization of the obtained monomer with oligo(ethylene glycol)acrylate (OEGA) gave well-defined P(ACL-co-OEGA) with low distribution. Nuclear magnetic resonance , size exclusion chromatography, and matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry measurements indicated the controlled feature of the polymerization. Moreover, the resultant copolymers demonstrated thermoresponsiveness, and the cloud points (T-cp) can be adjusted from 34 to 79 degrees C, by changing pH values, and the fraction of cyclic lysine. These results suggested that these lysine-based thermoresponsive polymers might be used as new materials in biomedical fields. (c) 2019 Wiley Periodicals, Inc.