Synthesis And Characterization Of Photorefractive Change Polymers And Molecular Glass Materials

In this dissertation, six multifunctional photorefractive polymers and eight photorefractive organic molecular glasses were designed and synthesized with an aim to simplify preparation and improve the PR performance of materials. These novel PR materials were characterized by NMR, UV-visible and IR spectroscopies, GPC, DSC, TGA and elemental analysis. The photorefractive properties of these materials were measured by using two-beam coupling (TBC) and four-wave mixing (FWM) techniques and interpreted in terms of the structure-property correlation.Post-azo-coupling reaction was successfully applied to synthesize a series of photorefractive polyphosphazenes P6-P10 containing carbazole-based multifunctional chromophores. The polymers show low glass transition temperatures, and exhibit excellent solubility in common organic solvents, which can easily be fabricated into an optically transparent film with long-term stability. Single-component polymers P6-P8 exhibited good PR performance at room temperature without external electric field or prepoling and gain coefficient as high as 91cm^-1 was observed in the polymer with the lowest glass transition temperature (P8). Gain coefficient of 198cm^-1 and diffraction efficiency of 46% was obtained in P6 doped with 20% ECZ. The possible forming process of all-optical photorefractive effect was suggested and the structural effects of polymers were explored on the glass transition temperature, chromophore loading, as well as the optical gain.Similar procedure was used to synthesize two hyper-structured molecular glasses M1-M2 with a cyclotriphosphazene core. Since these molecules have a highly branched structure, they exhibit excellent solubility in common organic solvents and show complete vitrification. TBC and FWM measurements were used to prove the PR performance in the optically transparent films formed by adding 30% ECZ to Ml and M2. With no external electric field, gain coefficient of 102cm^-1 and diffraction efficiency of 24% were obtained in the composite made from Ml, and even higher gain coefficient of 214cm^-1 and diffraction efficiency of 31% were obtained in the...