Superhydrophilic zwitterionic poly(ethyl methacrylate)-b-poly(carboxybetaine methacrylate) copolymers with highly...

This study presents for the first time the synthesis and characterization of superhydrophilic zwitterionic poly(ethyl methacrylate)-b-poly(carboxybetaine methacrylate) (PEMA-b-PCBMA) copolymers. The copolymers prepared using a multi-step Reversible Addition-Fragmentation chain-transfer (RAFT) polymerization method were designed with nearly constant PCBMA length while systematically increasing the length of the hydrophobic PEMA block to study its impact on polymers' self-assembly. Critical concentration and aggregation behavior were investigated across various physiological media, including water, 0.9% NaCl, phosphate buffer saline (PBS), and acidic (pH 3) solutions. The copolymer chains successfully self-assembled into stable, well-defined spherical core-shell micelles in all studied media at critical concentrations. The CMC value clearly depends on the length of hydrophobic block and its fraction in copolymers. Above critical concentration aggregation appears, leading to formation of additional large particles. The environmental factors, i.e. presence of salts and pH, were responsible for the size of particles. After 3 months of storage, no size-changes were observed for the dispersions of micelles in the studied aqueous media formed by copolymers with the lowest hydrophobic fraction while for the copolymer with the highest fraction only large aggregates were present.