Thermoresponsive Poly(α-peptoid)s: Tuning the Cloud Point Temperatures by Composition and Architecture

Random copolymers based on poly(N-ethyl glycine) and poly(N-butyl glycine) have been synthesized by NHC-mediated or primary amine-initiated copolymerization of the corresponding N-substituted N-carboxyanhydride monomers (i.e., Et-NCA and Bu-NCA), respectively. The copolymers are thermally responsive and exhibit reversible phase transitions with tunable cloud point temperature (T_cp) in aqueous solution. The T_cp can be readily tuned in the temperature range 20-60 °C by controlling the copoly(α-peptoid) composition and the architecture (i.e., cyclic vs linear). The copoly(α-peptoid)s are noncytotoxic (similar to poly(ethylene glycol) (PEG), a benchmark biocompatible polymer), suggesting their potential use in biotechnology and biomedicine.