Water Soluble Thermoresponsive Single-Chain Cyclized/Knotted Polymers from Intramolecular Cyclization Dominated Homopolymerization of PEG Diacrylate.

Abstract

A series of water-soluble, PEG-based single-chain cyclized/knotted polymers are successfully synthesized through the homopolymerization of poly(ethylene glycol) diacrylate (PEGDA) (M_n  = 575 and 700 g mol^-1, respectively) via enhanced intramolecular cyclization. The homopolymerization of the diacrylate macromers first proceeds through linear propagation, followed by self-cyclization. Under high monomer-to-initiator ratios (e.g., 100-500) and room temperature, cyclized polymers with high cyclized ratios of up to 70% are achieved without gelation. Notably, the cyclized poly(PEGDA₅₇₅) exhibits concentration-dependent thermoresponsive properties in aqueous solutions.