Robust polyazobenzene microcapsules with photoresponsive pore channels and tunable release profiles

Structure of pore channels in the shell of PAzo microcapsules and release curves of RhB from PAzo microcapsules. Monodisperse silica particles coated with azobenzene polymer (PAzo) shell were synthesized through distillation precipitation polymerization. Robust PAzo microcapsules were obtained after...

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Bibliographic Details
Published in:European polymer journal 2012, Vol.48 (1), p.41-48
Main Authors: Wang, Xiaotao, Yang, Yingkui, Liao, Yonggui, Yang, Zhifang, Jiang, Man, Xie, Xiaolin
Format: Article
Language:English
Subjects:
Acetonitrile
Applied sciences
Azobenzene
Channels
Controlled release
Exact sciences and technology
Forms of application and semi-finished materials
Microcapsules
Miscellaneous
Photoresponsive behavior
Polymer industry, paints, wood
Polymerization
Porosity
Shells
Silicon dioxide
Switches
Technology of polymers
Ultraviolet
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Summary:Structure of pore channels in the shell of PAzo microcapsules and release curves of RhB from PAzo microcapsules. Monodisperse silica particles coated with azobenzene polymer (PAzo) shell were synthesized through distillation precipitation polymerization. Robust PAzo microcapsules were obtained after selective removal of the silica templates by hydrofluoric acid (HF) etching. These PAzo microcapsules, confirmed by transmission electron microscopy (TEM) investigation, had excellent reversible photoisomerization with transformation between trans and cis isomers under ultraviolet (UV) and visible lights. Due to their compatibility with PAzo, acetonitrile would be trapped in the network of the shell during polymerization. Pore channels in the shell, confirmed by nitrogen adsorption–desorption test, would be produced after acetonitrile evaporation. Loading and release of rhodamine B (RhB) molecules in PAzo microcapsules were carried out and indicated that cis azobenzene showed larger pore diameter (named as “open switch”) under UV light which favored permeation of RhB molecules, while trans structure (named as “closed switch”) under visible light slowed down the process. In addition, both release profiles obeyed pure Fickian diffusion with a power law of t 0.42. Diffusion coefficient of RhB from PAzo microcapsules under visible light (1.47 × 10 −12 cm 2/s) was lower than that under UV light (2.12 × 10 −12 cm 2/s).
ISSN:0014-3057
1873-1945
DOI:10.1016/j.eurpolymj.2011.10.012