Dual‐Functional Cationic Bottlebrush Copolymer/Polyethersulfone Blend Membranes With Antibacterial and Antifouling Properties

Bottlebrush copolymers exhibit enhanced conformational stability and have potential for antibacterial and antifouling materials. In this work, cationic bottlebrush copolymers composed of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and quaternized 2‐(dimethylamino)ethyl methacrylate (QDMAEMA) were synthesized via controllable atom transfer radical polymerization. The as‐prepared bottlebrush copolymers were subsequently blended with polyethersulfone to fabricate robust membranes with combined antibacterial and antifouling properties. Compared to their linear analogues, the bottlebrush copolymer‐based membranes exhibited enhanced antibacterial efficacy against Escherichia coli and Staphylococcus aureus , along with faster bactericidal kinetics. This improvement is attributed to the increased surface exposure of quaternary ammonium groups in the bottlebrush architectures, which strengthen electrostatic interactions with negatively charged bacteria. Additionally, the densely packed side‐chain arrangement stabilized hydration layers, thereby suppressing protein adsorption and bacterial adhesion. Notably, the optimized bottlebrush copolymer‐based membranes exhibited excellent durability, retaining over 99% antibacterial activity after five cycles. Hemolysis and cytotoxicity assays confirmed that the bottlebrush copolymer‐based membranes were biocompatible with mammalian cells. Our results highlight a topology‐based strategy for fabricating functional materials with synergistic antibacterial and antifouling capabilities.