In situ observation of azobenzene isomerization along with photo-induced swelling of cross-linked vesicles by laser-trapping Raman spectroscopy

Guangyong Shen; Guosheng Xue; Jun Cai; Gang Zou; Yinmei Li; Mincheng Zhong; Qijin Zhang

doi:10.1039/C2SM25963J

In situ observation of azobenzene isomerization along with photo-induced swelling of cross-linked vesicles by laser-trapping Raman spectroscopy

Guangyong Shen,^a Guosheng Xue,^b Jun Cai,^a Gang Zou,^a Yinmei Li,^b Mincheng Zhong^b and Qijin Zhang*^a

* Corresponding authors

^a Key Laboratory of Soft Matter Chemistry, Key Laboratory of Optoelectronic Science and Technology, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, P. R. China
E-mail: zqjm@ustc.edu.cn
Fax: +86 551 3601 704

^b Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, P. R. China

Abstract

Laser-trapping Raman spectroscopy (LTRS) is adopted to detect the photo-induced isomerization of azobenzene in the cross-linked membrane of a single vesicle, which is self-assembled first by an amphiphilic copolymer, poly(N-isopropylacrylamide)-block-poly{6-[4-(4-pyridyazo)phenoxy]hexylmethacrylate} (PNIPAM-b-PAzPy6), and then cross-linked by reaction between 1,3-dibromopropane and pyridine groups in the copolymer chain. A series of polymer vesicles with different cross-linking degrees were made to meet the need of vesicles with different softness during this research work. Vesicles with 0.0% and 18.7% cross-linking degrees have characteristic photo-induced swelling–shrinking, others with higher cross-linking degrees do not. The isomerization of azobenzene is observed in situ by LTRS along with photo-induced swelling of single vesicles with different cross-linking degrees. Results from analysis of the obtained Raman spectra show that photo-induced isomerization of azobenzene is a trigger of the photo-induced swelling process and the swelling degree is mainly dependent on the degree of cross-linking, namely, the softness of the polymer vesicle. The former result is different from that obtained by analysis of UV-Vis spectroscopy for vesicle solutions and shows that photo-induced swelling–shrinking vesicles can be constructed by amphiphilic copolymers bearing azobenzene units in the minority.

Supplementary files

Publication details

The article was received on 25 Apr 2012, accepted on 19 Jun 2012 and first published on 27 Jul 2012

Article type: Paper

DOI: 10.1039/C2SM25963J

Citation: Soft Matter, 2012,8, 9127-9131

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In situ observation of azobenzene isomerization along with photo-induced swelling of cross-linked vesicles by laser-trapping Raman spectroscopy

G. Shen, G. Xue, J. Cai, G. Zou, Y. Li, M. Zhong and Q. Zhang, Soft Matter, 2012, 8, 9127
DOI: 10.1039/C2SM25963J
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Soft Matter

In situ observation of azobenzene isomerization along with photo-induced swelling of cross-linked vesicles by laser-trapping Raman spectroscopy

Abstract

Supplementary files

Publication details

In situ observation of azobenzene isomerization along with photo-induced swelling of cross-linked vesicles by laser-trapping Raman spectroscopy

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