title: Liquid/Liquid interfacial fabrication of thermosensitive and catalytically active Ag nanoparticle-doped block copolymer composite foam films.
abstract: An aqueous solution of AgNO3 (upper phase) and a DMF/CHCl3 solution of polystyrene-b-poly(acryl acid)-b-polystyrene (PS-b-PAA-b-PS) or PS-b-PAA-b-PS/1,6-diaminohexane (DAH) (lower phase) constituted a planar liquid/liquid interface. The lower phase gradually transformed to a water-in-oil (W/O) emulsion via spontaneous emulsification due to the "ouzo effect". Polymer molecules, DAH molecules, and Ag(+) ions assembled into microcapsules around emulsion droplets that adsorbed at the planar liquid/liquid interface, resulting in formation of a foam film. DAH acted as a cross-linker during this process. Transmission electron microscopic observations indicated that Ag nanoclusters that were generated through reduction of Ag(+) ions by DMF were homogeneously dispersed in the walls of the foam structure. X-ray photoelectron spectroscopic investigations revealed that Ag(I) and Ag(0) coexisted in the film, and Ag(I) transformed to Ag(0) after further treatment. The film formed without DAH was not stable, while the film formed with DAH was very stable due to intermolecular attraction between PAA and DAH and formation of amides, as revealed by FTIR spectra. The film formed with DAH exhibited high and durable catalytic activity for hydrogenation of nitro compounds and, very interestingly, exhibited thermoresponsive catalytic behavior.
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University , Jinan 250100, P. R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Liu
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Geng
authors.forename: Changwei
authors.initials: C
authors.lastname: Wang
authors.forename: Yong-Ill
authors.initials: YI
authors.lastname: Lee
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao
authors.forename: Hong-Guo
authors.initials: HG
authors.lastname: Liu