title: Ion-specific oil repellency of polyelectrolyte multilayers in water: molecular insights into the hydrophilicity of charged surfaces.
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.
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095 (Australia).
authors.forename: Xiaokong
authors.initials: X
authors.lastname: Liu
authors.forename: Chuan
authors.initials: C
authors.lastname: Leng
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Ke
authors.initials: K
authors.lastname: He
authors.forename: Lauren Joan
authors.initials: LJ
authors.lastname: Brown
authors.forename: Zhan
authors.initials: Z
authors.lastname: Chen
authors.forename: Jinhan
authors.initials: J
authors.lastname: Cho
authors.forename: Dayang
authors.initials: D
authors.lastname: Wang
mesh_terms: D004573:Electrolytes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions / Q000737:chemistry; D000066388:Oil and Gas Industry; D009821:Oils / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011095:Polyethylenes / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D004573:Electrolytes; D007477:Ions; D009821:Oils; D011095:Polyethylenes; D011137:Polystyrenes; D000644:Quaternary Ammonium Compounds; D014867:Water; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; C003321:polystyrene sulfonic acid
keywords: interfaces; oil-water separation; photoelectronspectroscopy; structure elucidation; surface chemistry