title: Fabrication of a Self-Cleaning Surface via the Thermosensitive Copolymer Brush of P(NIPAAm-PEGMA).
abstract: Surface hydrophilicity and the inherent washing force are two crucial factors for constructing an underwater self-cleaning surface. Following this self-cleaning mechanism, we fabricated thermosensitive copolymer brushes of N-isopropylacrylamide (NIPAAm) and poly(ethylene glycol) methacrylate (PEGMA) on the polypropylene (PP) surface. Benefiting from the hydrophilic poly(ethylene glycol) (PEG) side chains, the copolymer brushes with the PEGMA content exceeding 5 mol % exhibited good surface hydrophilicity, whenever at temperatures below or above the lower critical solution temperatures (LCST). Hence their underwater oleophobicity was greatly improved with oil contact angles higher than 141° and oil adhesive forces lower than 20 μN. In addition, the sharp volume-phase transition feature was reserved in their copolymer backbones, as proved by the AFM result. Self-cleaning evaluation of the modified surfaces was performed by a simple temperature-change water cleaning method, after which only 0.2 wt % of oil residues remained on the brush surface of P(NIPAAm-5PEGMA) (with 5 mol % of PEGMA contents). The excellent self-cleaning capability is believed to be ascribed to its balanced surface features in hydrophilicity and the sharper volume-phase transition, when a hydrophilic surface can facilitate oil desorption and an intense conformation change of chain stretching and shrinking can offer the strong washing force to assist oil detachment. This study contributes to development of the underwater self-cleaning surface based on a hydrophilic surface with the chain motion.
authors.affiliation: College of Material Science and Engineering, Nanjing Tech University , Nanjing 210009, China.
authors.forename: Yuansong
authors.initials: Y
authors.lastname: Ye
authors.affiliation: College of Material Science and Engineering, Nanjing Tech University , Nanjing 210009, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Chemical Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
keywords: poly(N-isopropylacrylamide); poly(ethylene glycol); self-cleaning surface; surface hydrophilicity; volume-phase transition; washing force