Side-based Discotic Liquid Crystal-based Poly Benzene Synthesis And Characterization,

A new discotic mesogen of phenyl core with three alkoxy phenylacetylene has been synthesized. The discotic mesogen was linked to 1, 4-Dibromo-2-bromomethyl-benzene via a short spacer. The product was characterized by ¹HNMR and ¹³CNMR. The results confirmed the structure of the products.Three polymers were obtained through homopolymerization and copolymerization. The molecular weights, thermal behaviors, liquid crystal behavior and optical properties of the polymers were characterized through GPC, TG, DSC, POM, XRD, Uv-vis and PL. The results indicated that the polymers have good thermal stability, exhibit amorphous status at room temperature and show mesophase when pressure force was applied at 170℃. The influence of the lateral-group-density (LGD) on the thermal behaviors and optical properties of the polymers was evaluated. It is found that the LGD has little effect on the molecular weights of the polymers. On the other hand, the glass transfer temperatures (Tg) of polymers increase as the LGD decrease. The decrease of LGD also makes a blue shift in photoluminescence (PL) spectra. The morphology of the polymers has strong effect on the optical properties of the polymers. The two copolymers have a near ultraviolet photoluminescence emission in THF solution, and the homopolymer show a blue PL emission. The spin films and annealed films of the polymers have red shifted about 100nm compared with that of the THF solution and show a yellow-green emission. This phenomenon is attributed to the formation of excimer in the solid state.Meanwhile, a primer study of the influence of the lateral-group-alkoxy-length to the thermo-behaviors and optical properties of the polymer has been developed.