Accession Number : ADA322374

Title :   Synthesis and Optical Properties of Polyureas with Azoaromatic Groups in the Main Chain.

Descriptive Note : Technical rept.,

Corporate Author : MASSACHUSETTS UNIV LOWELL DEPT OF CHEMISTRY

Personal Author(s) : Lee, T. S. ; Kim, D. Y. ; Jiang, X. L. ; Li, L. ; Kumar, J.

PDF Url : ADA322374

Report Date : 06 FEB 1997

Pagination or Media Count : 26

Abstract : We report the synthesis and optical properties of two different polyureas containing azo units in the main chain. The polymers were synthesized from the reaction between a diisocyanate and a diaminoazo compound (4,4' -diaminoazobenzene) with good yield. These polyureas had glass transition temperatures around 197 deg C and the films of these polymers showed an absorption maximum at 380 nm due to the azo chromophore. Upon polarized laser irradiation at 488nm, dichroism was optically induced in these main-chain azoaromatic polymers with a fairly high glass transition temperature. In addition we observed a degree of polar order by corona poling and a build up of second harmonic signal. It is conjectured that the induced order results mainly from an alignment of azo units through trans-cis trans isomerization, as well as from the molecular rearrangement of the polyurea backbone. We further observed regularly-spaced surface relief gratings on the polyurea film upon exposure to an interference pattern of polarized argon laser beams. Large scale molecular migration in this high Tg polymer at room temperature has been achieved for the first time.

Descriptors :   *OPTICAL PROPERTIES, *POLYMERS, *UREA, *DIAZO COMPOUNDS, POLARIZATION, SYNTHESIS, CHROMOPHORES, MOLECULES, SECOND HARMONIC GENERATION, HIGH TEMPERATURE, FILMS, GLASS, LASER BEAMS, ROOM TEMPERATURE, ALIGNMENT, CHEMICAL BONDS, TRANSITION TEMPERATURE, SIGNALS, INTERFERENCE, PATTERNS, MIGRATION, IRRADIATION, ARGON LASERS, ISOMERIZATION, DICHROISM.

Subject Categories : Polymer Chemistry
      Organic Chemistry
      Lasers and Masers
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE