Photoresponsive polymers: An investigation of their photoinduced temperature changes during photoviscosity measurements

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

Abstract

Photoresponsive polyelectrolyte of polyacrylic acid with spiropyran in the side chain was synthesized by reacting polyacryloyl chloride with 1'-(2-hydroxyethyl)-3',3'-dimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-ind oline] and by subsequent hydrolysis of acid chloride. The conformation of this material was photomampulated and the associated changes in viscosity were studied by using a custom-modified rheometer. It was observed that the specific viscosity of the spiropyran-based polymer solution increased by about 12% upon UV irradiation and decreased due to visible irradiation. The viscosity changes were found to be reversible. The photoinduced heating effects during in situ photoviscosity measurements on two classes of materials, the polyelectrolyte and a series of azobenzene-based polymers, were also measured using a modified rheometer cone. The origin and magnitude of the heating effect were identified, and the associated viscosity changes of the solutions were decoupled to obtain a more accurate view of the photoviscosity behaviour. The magnitude of the photoinduced heating effect was found to be linearly dependent on chromophore molecules joined to the polymer chains. The photoinduced heating effect accounted for varying amounts of the observed change in specific viscosity ranging from as little as 2.5% for a highly photoresponsive solution to all of the observed specific viscosity change measured for non-photoresponsive systems. (c) 2006 Published by Elsevier Ltd.

Details

Original languageEnglish
Pages (from-to)255-263
Number of pages9
JournalPolymer
Volume48
Issue number1
Publication statusPublished - 5 Jan 2007