Scalable and switchable CO2-responsive membranes with high wettability for separation of various oil/water systems
Yangyang Wang, Shaokang Yang, Jingwei Zhang, Zhuo Chen, Bo Zhu, Jian Li, Shijing Liang, Yunxiang Bai, Jianhong Xu, Dewei Rao, Liangliang Dong, Chunfang Zhang, Xiaowei Yang
Abstract
Abstract Smart membranes with responsive wettability show promise for controllably separating oil/water mixtures, including immiscible oil-water mixtures and surfactant-stabilized oil/water emulsions. However, the membranes are challenged by unsatisfactory external stimuli, inadequate wettability responsiveness, difficulty in scalability and poor self-cleaning performance. Here, we develop a capillary force-driven confinement self-assembling strategy to construct a scalable and stable CO 2 -responsive membrane for the smart separation of various oil/water systems. In this process, the CO 2 -responsive copolymer can homogeneously adhere to the membrane surface by manipulating the capillary force, generating a membrane with a large area up to 3600 cm 2 and excellent switching wettability between high hydrophobicity/underwater superoleophilicity and superhydrophilicity/underwater superoleophobicity under CO 2 /N 2 stimulation. The membrane can be applied to various oil/water systems, including immiscible mixtures, surfactant-stabilized emulsions, multiphase emulsions and pollutant-containing emulsions, demonstrating high separation efficiency (>99.9%), recyclability, and self-cleaning performance. Due to robust separation properties coupled with the excellent scalability, the membrane shows great implications for smart liquid separation.