Functionalized Photorefractive Monomers, Their Synthesis,Polymerization And Characterization Of Related Polymers

With the aim of bi-functionalized photorefractive polymers bearing a non-conjugated main chain (NCMC), three series of novel carbazole-based functionalized monomers were designed and synthesized by introduction of the oxirane and norbornene groups. Then, corresponding non-conjugated main chain polymers were synthesized via cationic ring-opening polymerization or ring-opening metathesis polymerization, among which14polymers were not reported before.Firstly, two functional monomers with oxriane group were obtained via the reaction of carbazole-based compounds with epichlorohydrin (EPC). One monomer was with an azobenzene chromophore and the other was not. Then, photorefractive poly(ethylene oxide) s were synthesized via cationic ring-opening polymerization using boron trifluoride etherate (BTE) as an initiator. Polymers were characterized by IR, GPC, UV-vis, TG and DSC, etc. Their number average molecular weights (Mn) are less than2000because of the mismatching of monomer with initiator. All the polymers have good thermostablity. Glass transition temperature of the obtained polymers decreases with the increase in the feed ratio of M2. The UV-vis absorption maxima are almost the same.In the second part, in order to obtain polymers with higher molecular weights, four functionalized monomers with norbornene groups were designed and synthesized. Corresponding polymers were prepared via ring-opening metathesis polymerization (ROMP) using Grubbs1or Grubbs2as a catalyst. The polymers were characterized by IR. UV-Vis, GPC, DSC and TG, etc. Their number average molecular weights (Mn) are higher than1.0×104, and the catalytic activity of the Grubbs2is higher than that of Grubbs1. The polymers have good thermal stability up to280℃and excellent solubility in THF, and their glass transition temperatures are in the range from43℃to153℃depending on the content of functional group and spacer length.In the third part, two norbornene monomers with methine chromophore were further designed and synthesized via Vilsmeyer and Knoevenagel reactions. In addition, a norbornene monomer with a longer alkyl spacer between the functional chromophore and carbazole group was synthesized.1H NMR, IR and elementary analysis proved the successful synthesis. Corresponding polymers were prepared via ROMP using Grubbs2catalyst and were characterized by IR, UV-Vis, GPC, DSC and TG, etc. Their number average molecular weights (Mn) are higher than5.0×104and their glass transition temperatures are in the range from18℃to101℃.Finally, optically transparent films were fabricated with N-ethyl-carbazole (ECZ) as a plasticizer and C60or TNF as a charge generator in norbornene polymers with azo-benzene chromophore. Their photorefractive performance was evaluated at633nm by two-beam-coupling (TBC) experiment at a zero electrical field or electrical field without prepoling. TBC signals were observed from these films, indicating that the synthesized NCMC polymers bear an all-optical photorefractive behavior. In addition, Single component polymers P15and P16also bear an all-optical photorefractive behavior.