Investigation of spiropyrans and merocyanines in mixed thin films with long chain alkyl silanes: Towards a command surface for liquid crystal realignment
Galvin, Jennifer Marie
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https://hdl.handle.net/2142/20043
Description
Title
Investigation of spiropyrans and merocyanines in mixed thin films with long chain alkyl silanes: Towards a command surface for liquid crystal realignment
Author(s)
Galvin, Jennifer Marie
Issue Date
1996
Doctoral Committee Chair(s)
Schuster, Gary B.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Organic
Physics, Condensed Matter
Language
eng
Abstract
Spiropyran derivatives containing a variable-length linking chain and either tri- or mono-alkoxy silane end groups were synthesized. Glass slides were deposited with mixed thin films of the spiropyran compounds and either octadecyltrimethoxysilane or octadecyldimethylmethoxysilane. The photochemistry of the spiropyran in the thin films was characterized by UV-Vis spectroscopy. Irradiation of the films causes the formation of the open form of the spiropyran, which can be detected by absorption spectroscopy. The rate of the thermal reaction from the open (merocyanine) to the closed form of the spiropyran was measured, and shows no dependence on the length of the spiropyran molecule, though the rate is much closer to that found for spiropyran molecules doped into polymers than in solution. Sessile drop contact angle measurements show a decrease from 70 $\pm$ 3 degrees to 63 $\pm$ 2 degrees for films prepared from the trialkoxy silanes upon irradiation with UV light. Evaluation of this system as a surface to control the realignment of the nematic liquid crystal K-15 proved unsuccessful, though the surface energy of the systems can be changed solely by irradiation with light.
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