Ammonium-Containing Methacrylic Polymer Brushes with Adjustable Hydrophilicity: Synthesis and Properties in Aqueous Solutions

Reversible addition-fragmentation chain-transfer (RAFT) polymerization was used to synthesize novel thermoresponsive cationic molecular brushes with high yields-namely of copolymers of methoxyoligo(ethylene glycol) methacrylate, alkoxyoligo(ethylene glycol) methacrylate, and N-methacryloylaminopropyl-N,N-dimethyl-N-propylammonium bromide. Controlled polymerization yielded polymers with a molecular weight dispersity of ≤1.3 and conversions exceeding 80%. The influence of the cationic molecular brushes' composition on their solubility in water and organic solvents, interfacial tension at the water-oil interface, and aggregation behavior in aqueous solutions was investigated. For the first time, we report the design of thermoresponsive cationic molecular brushes combining an antibacterial potential and tunable hydrophilic-hydrophobic properties, enabling highly precise control over their LCST behavior (17-68 °C) through composition tuning. The solubilization capacity of the hydrophobic compounds of brush micelles in water increased with the hydrophobic comonomer content. These polymers exhibited interfacial activity, significantly reducing the water-oil interfacial tension, with critical micelle concentrations (CMCs) of 3-10 mg/L. It was shown that the amphiphilic properties of the copolymers in aqueous solutions can be easily tuned in a desired direction by varying the content of the comonomer units. The obtained data indicate the potential of the polymers as micellar nanocarriers for controlled drug delivery.