title: Emulsion-directed liquid/liquid interfacial fabrication of lanthanide ion-doped block copolymer composite thin films.
abstract: An emulsion-directed assembly and adsorption approach has been used to fabricate composite films of polystyrene-b-poly(acryl acid)-b-polystyrene (PS-b-PAA-b-PS) and Eu(3+) and La(3+) ions at the planar liquid/liquid interface of the polymer DMF/chloroform (1:1, v/v) mixed solution (lower phase) and aqueous solutions of the corresponding salts (upper phase). The lower phase gradually transformed to a water-in-oil (W/O) emulsion via spontaneous emulsification due to the "ouzo effect". Polymer molecules and the metal ions assembled around emulsion droplets that adsorbed at the planar liquid/liquid interface at last, resulting in formation of composite films. The film morphologies and structures depend on Ln(3+) ions: polymer/Eu(3+) composite films were foam films composed of microcapsules ranging in size from several hundreds of nanometers to micrometers, while polymer/La(3+) composite films were composed of hollow spheres several tens of nanometers in size. Fourier transform infrared (FTIR) spectra revealed that the coordination modes of carboxyl groups to Eu(3+) and La(3+) were bridging bidentate and ionic, respectively, in the two types of composites. These results indicate that stable microcapsules can be fabricated around droplets for polymer/Eu(3+) systems, while microcapsules of polymer/La(3+) are unstable. This leads to different film morphologies and structures. Compositions of these films were characterized using energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). In addition, foam films of polymer/Eu(3+)/2,2'-bipyridine (bpy) were fabricated using this approach, and their photoluminescence properties were investigated.
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100, PR China.
authors.forename: Ming
authors.initials: M
authors.lastname: Hong
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100, PR China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100, PR China.
authors.forename: Mei
authors.initials: M
authors.lastname: Liu
authors.affiliation: School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Anastro Laboratory, Department of Chemistry, Changwon National University, Changwon 641-773, Republic of Korea.
authors.forename: Yong-Ill
authors.initials: YI
authors.lastname: Lee
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100, PR China.
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100, PR China. Electronic address: hgliu@sdu.edu.cn.
authors.forename: Hong-Guo
authors.initials: HG
authors.lastname: Liu
keywords: Adsorption; Block copolymer; Composite film; Emulsion; Liquid/liquid interface; Luminescence