PhotoATRP-Based Fluorinated Thermosensitive Block Copolymer for Controllable Water/Oil Separation

The increasing environmental burden in human society calls for the development of more environmentally benign technologies and sustainable applications. Wastewater contaminated by oil or organic solvents has become a serious environmental issue nowadays. Herein, a well-defined thermosensitive block copolymer was designed and used for controllable water/oil separation. The functional material poly(2,2,3,4,4,4-hexafluorobutyl methacrylate)-block-poly(N-isopropylacrylamide) was synthesized through a new environmentally benign "living" radical polymerization technique [i.e., photoinitiated atom-transfer radical polymerization (photoATRP)]. The synthesized functional copolymer was considered as a modifier for fabricating a smart surface with thermal-responsive wettability. The switchable mechanism, surface composition, and morphology of the as-fabricated surface were investigated by water contact-angle measurement, X-ray photoelectron spectroscopy, and atomic force microscopy. Results showed that the as-fabricated surface can reversibly switch between the hydrophilicity and hydrophobicity, which results from the synergistic effect of surface chemical composition, reorientation of the functional groups, and roughness in response to the temperature. On the basis of mechanism understanding, a smart separation device was constructed and used for separating water/oil mixtures. The separation of a water/hexane layered mixture has high penetration fluxes of 2.50 L s(-1) m(-2) for water and 2.78 L s(-1) m(-2) for hexane, while exhibiting a good efficiency of over 98%.