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7943234 
Journal Article 
Refractive index modulation in the polyurethane films containing diazo sulfonamide chromophores 
Ortyl, E; Kucharski, S; Gotszalk, T 
2005 
1 
Thin Solid Films
ISSN: 0040-6090
EISSN: 1879-2731 
479 
1-2 
288-296 
English 
WOS:000228372100042 
The series of photochromic polyurethanes was obtained by modification of precursor polymers prepared from 4,4′-diphenylmethane diisocyanate (MDI), hexamethylene 1,6-diisocyanate (HDI) or toluene 2,4-diisocyanate (TDI) and N,N'-di-(2-hydroxyethyl) aniline. The precursor polymers were functionalized by an azo-coupling reaction to form the polymers with different degrees of functionalization and various heterocyclic sulfonamide groups. Ellipsometric measurements showed a decrease of the refractive index during illumination of thin polymer films with white light. The change of real part of the refractive index was in the range of 0.0033-0.0296 depending on the polymer kind and chromophore content. It was found that photocurrent was generated in the polymer films deposited onto indium tin oxide (ITO) glass plates. For the polyurethanes containing sulfathiazole groups in side chains the current density was up to 180 nA/cm2. The formation of diffraction grating in the polymer films was easily achieved using linearly polarized laser light (532 nm) in a standard two beam coupling (TBC) system. The diffraction efficiency of the first diffraction beam was dependent on the chromophore content reaching ca. 12% for the derivatives of sulfamethoxazole. 2004 Elsevier B.V. All rights reserved. 
photochromic polyurethane films; Trans-cis isomerisation; diffraction grating; diazo sulfonamide chromophores