Ion‐Specific Oil Repellency of Polyelectrolyte Multilayers in Water: Molecular Insights into the Hydrophilicity of Charged Surfaces |
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| Authors: | Dr Xiaokong Liu Chuan Leng Li Yu Ke He Lauren Joan Brown Prof?Dr Zhan Chen Prof?Dr Jinhan Cho Prof?Dr Dayang Wang |
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| Institution: | 1. Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095 (Australia);2. Department of Chemistry, University of Michigan, Ann Arbor, MI 48109 (USA);3. Department of Chemical and Biological Engineering, Korea University, Seoul, 136–701 (Korea) |
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| Abstract: | Surface wetting on polyelectrolyte multilayers (PEMs), prepared by alternating deposition of polydiallyldimethylammonium chloride (PDDA) and poly(styrene sulfonate) (PSS), was investigated mainly in water‐solid‐oil systems. The surface‐wetting behavior of as‐prepared PEMs was well correlated to the molecular structures of the uncompensated ionic groups on the PEMs as revealed by sum frequency generation vibrational and X‐ray photoelectron spectroscopies. The orientation change of the benzenesulfonate groups on the PSS‐capped surfaces causes poor water wetting in oil or air and negligible oil wetting in water, while the orientation change of the quaternized pyrrolidine rings on the PDDA‐capped surfaces hardly affects their wetting behavior. The underwater oil repellency of PSS‐capped PEMs was successfully harnessed to manufacture highly efficient filters for oil‐water separation at high flux. |
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| Keywords: | interfaces oil‐water separation photoelectronspectroscopy structure elucidation surface chemistry |
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