Molecular orientation and liquid crystal alignment properties of new cinnamate-based photocrosslinkable polymers

Autor:	Claude Sourisseau, Jacques A. Delaire, Sebastien Perny, P. Le Barny, Thierry Buffeteau
Rok vydání:	2000
Předmět:	chemistry.chemical_classification Materials science Linear polarization General Chemistry Polymer Chromophore Condensed Matter Physics Polarization (waves) Linear dichroism Cycloaddition Crystallography chemistry Liquid crystal Organic chemistry General Materials Science Isomerization
Zdroj:	Liquid Crystals. 27:341-348
ISSN:	1366-5855 0267-8292
DOI:	10.1080/026782900202787
Popis:	Isotropic thin films of three original phenyl substituted cinnamate-based polymers, here-after referred to as 'Para', 'Meta' and 'Metamet' have been exposed to linearly polarized UV light and their photoinduced molecular orientations have been studied. The resulting photocrosslinked anisotropic polymer films were characterized using UV, conventional and polarization modulation (PM) FTIR spectroscopies. From UV and PM-IR linear dichroism measurements, at least two simultaneous orientation processes appear to play a key role in these phenyl substituted cinnamate-based systems. On the one hand, isomerization reactions deplete chromophores along the polarization direction (P) of the UV light and induce a preferential orientation of remaining 'trans'-isomers perpendicular to P; on the other hand, cycloaddition reactions lead to the formation of either head to head or head to tail photodimers aligned preferentially along P in the 'Para' and to a lesser extent in the 'Meta' and 'Metamet' systems. These last resu...
Databáze:	OpenAIRE
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