title: Fabrication of free-standing polyelectrolyte multilayer films: a method using polysulfobetaine-containing films as sacrificial layers.
abstract: A new pH-dependent sacrificial system based on zwitterionic polysulfobetaine was proposed for the fabrication of free-standing polyelectrolyte multilayer films. The zwitterionic polysulfobetaine, poly(4-vinylpyridine propylsulfobetaine) (P4VPPS), was synthesized and its layer-by-layer (LbL) self-assembly behavior with poly(diallyldimethylammonium) (PDDA) as counterpart was investigated by using UV-vis absorption spectroscopy, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The LbL multilayer films of PDDA/P4VPPS were successfully constructed in acid aqueous solution at pH 2 with 0.5 M NaCl. The resultant PDDA/P4VPPS multilayer films were pH-dependent and could be disintegrated in alkali aqueous solutions, especially with pH > or = 12. This disintegration property rendered such multilayer film as a sacrificial layer for further preparing free-standing polyelectrolyte multilayer films. The PDDA/poly(sodium 4-styrenesulfonate) (PSS) multilayer films deposited on the PDDA/P4VPPS sacrificial layer were confirmed to be successfully released after treated successively by alkali aqueous solution at pH 12 and ethanol. The obtained PDDA/PSS free-standing multilayer films had thicknesses of ca. 847 nm.
authors.affiliation: Department of Polymer Science and Engineering, Zhejiang University, Key Laboratory of Macromolecular Synthesis and Functionalization (Ministry of Education), Hangzhou 310027, China.
authors.forename: Zhangliang
authors.initials: Z
authors.lastname: Gui
authors.forename: Jinwen
authors.initials: J
authors.lastname: Qian
authors.forename: Binyang
authors.initials: B
authors.lastname: Du
authors.forename: Mingjie
authors.initials: M
authors.lastname: Yin
authors.forename: Quanfu
authors.initials: Q
authors.lastname: An