Persistent, antimicrobial coating with self-cleaning surface function derived from contra-stoichiometric surface segregation of polyethylene glycol-block-poly(N-isopropylacrylamide)

The self-assembly of methoxypolyethylene glycol- block -poly (N-isopropylacrylamide) (mPEG- b -PNIPAAm) by thermal treatment resulted in excellent self-cleaning surface function upon water action, which arose from mPEG with surface coverage of 56% in contrast to their small stoichiometric fraction of ca. 17% in copolymers. This contra-stoichiometric surface segregation of mPEG caused weak but perceptible surface resistance against oil attachment in warm water. When thermo-sensitive mPEG- b -PNIPAAm membranes were subjected to chlorination of the amide groups of the PNIPAAm moieties, the exposed chains of mPEG not only had the ability of antibacterial adhesion, but also slowed down the release of oxidative chloride cations. Thanks to the surface segregation of mPEG, the membranes of mPEG- b -PNIPAAm had high antimicrobial efficacy up to 24 h over three consecutive antibacterial cycles; in contrast, chlorinated PNIPAAm membranes lost their antimicrobial performance after 4 h. Our mPEG- b -PNIPAAm exhibited a great potential application value in the fields of anti-infection treatment. • The as-prepared mPEG- b -PNIPAAm membranes show preferential surface segregation of the mPEG blocks over the PNIPAAm. • The as-prepared block films exhibited the excellent self-cleaning surface function with sensitivity to the temperature of the water phase. • The surface mPEG domains on the mPEG- b -PNIPAAm films can effectively block the contact with the PNIPAAm segments with the bacteria, and thus extending the antimicrobial efficacy upto 24 h for three consecutive antibacterial cycles.