Amphiphilic Random Copolymers with Hydrophobic/Hydrogen-Bonding Urea Pendants: Self-Folding Polymers in Aqueous and Organic Media

Abstract

Urea and poly(ethylene glycol) (PEG)-functionalized amphiphilic random copolymers served as self-folding polymers in both water and chloroform via hydrophobic and/or hydrogen-bonding interactions. For this, a urea-bearing methacrylate (BPUMA) was newly designed as a trigger monomer. Various random, gradient, and block copolymers were synthesized by living radical copolymerization of PEG methyl ether methacrylate (PEGMA) and BPUMA to systematically survey folding/association properties. Importantly, self-folding in both water and chloroform requires the random incorporation of BPUMA along a chain and the control of its composition, while gradient or block counterparts tend to induce multichain aggregation. Typically, 30–40 mol % BPUMA random copolymers effectively fold in water to form compact globular unimer micelles with hydrophobic/hydrogen-bonding core covered by multiple PEG arm chains. The dual functionalization of polymers with hydrophilic PEG and hydrophobic/hydrogen-bonding urea units afforded sin...