Triplet-Sensitized Irradiation of a Main-Chain Liquid Crystalline Poly(aryl Cinnamate) in Three Different Phases
Document Type
Article
Publication Date
1-1-2001
Department
Chemistry and Biochemistry
School
Mathematics and Natural Sciences
Abstract
Visible light irradiation of thin films of a main‐chain liquid crystalline poly(aryl cinnamate) using ketocoumarins as triplet sensitizers leads to photochemical crosslinking and UV‐vis and FTIR spectroscopic changes associated with saturation of the cinnamate double bond, most likely by 2 + 2 photocycloaddition. The triplet sensitizers are themselves photolabile and are lost by photochemical reactions during the sensitization process. A new ketocoumarin sensitizer with decyloxy substituents and a reduced tendency to phase separate from the polymer is reported. A simple calculation of the sensitization stoichiometry shows that a single molecule of this ketocoumarin sensitizes the destruction of approximately 90 cinnamate chromophores in the “as cast” films below Tg and about 300 chromophores in the more‐ordered glassy nematic films and in “as cast” films of poly(vinyl cinnamate). Triplet sensitization of fluid nematic films leads, upon initial irradiation, to UV‐vis hyperchromism that is attributed to disruption of chromophore aggregation and, possibly, to disruption of the nematic mesophase as photoproducts begin to form. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 134–144, 2001
Publication Title
Journal of Polymer Science Part A - Polymer Chemistry
Volume
39
Issue
1
First Page
134
Last Page
144
Recommended Citation
Creed, D.,
Hoyle, C.,
Jin, L.,
Peeler, A.,
Subramanian, P.,
Krishnan, V.
(2001). Triplet-Sensitized Irradiation of a Main-Chain Liquid Crystalline Poly(aryl Cinnamate) in Three Different Phases. Journal of Polymer Science Part A - Polymer Chemistry, 39(1), 134-144.
Available at: https://aquila.usm.edu/fac_pubs/9168