STABILITY OF PHOTOINDUCED ORIENTATION OF AN AZO COMPOUND INTO A HIGH-TG POLYMER

Optically induced birefringence on films containing disperse red 1 (DR1) doped into poly-(methyl methacrylate)(pMMA) and into a very high-T-g poly(ether ketone)(pASH) is compared with birefringence induced in films of a copolymer and a blend containing a similar azo moiety in the side chain. The level of the induced birefringence depends mainly on the film absorbance, as expected. The stability of the induced birefringence in the absence of illumination depends on the difference between room temperature (at which the experiment is performed) and the T-g of the material. Doping DR1 in a polymer depresses the material T-g producing a material that loses the birefringence very fast when the matrix is pMMA. All other materials, including pASH doped with DR1, show the usual high stability of the induced birefringence. Hence, doped high-T-g polymers may be suitable for reversible optical storage materials as the previously reported copolymers and blends, which had the azo moiety bound on the side chain.