Photoresponsive New Polysiloxanes with 4-Substituted Azobenzene Side-Groups. Synthesis, Characterization and Kinetics of the Reversible Trans-Cis-Trans Isomerization
✍ Scribed by Nicolae Hurduc; Dominique Adès; Joël Belleney; Alain Siove; Georges Sauvet
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 381 KB
- Volume
- 208
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
New polydimethylsiloxanes with p‐substituted azobenzene side‐groups were synthesized. Thin films and solutions exhibit a photochemical trans‐cis isomerization of the azobenzene groups, followed by their cis‐trans thermal relaxation in the dark. In films, relaxation rates were found to be 100–1 000 times slower than the rates of photoisomerization, the former being very sensitive to the electron‐acceptor character of the substituents. in solution, the rates of cis‐trans relaxation are lower than those obtained for the solid state. This is ascribed to the dipolar intramolecular interactions between cis chromophores, which are favored in solution.
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