Ring-opening metathesis polymerization of norbornene derivatives for multifunctionalized all-optical photorefractive polymers with a non-conjugated main chain

With the aim of multifunctionalized all-optical photorefractive polymers bearing a non-conjugated main chain (NCMC), four novel norbornene-containing monomers were synthesized by introduction of different alkyl spacers between the functional chromophore and norbornene group. The polymers were prepared via ring-opening metathesis polymerization (ROMP) and characterized by IR, UV-Vis, GPC, DSC, TG, etc. Their number average molecular weights (Mn) are higher than 1.0 × 104, and their glass transition temperatures are in the range from 75 °C to 153 °C depending on the volume of functional group and spacer length. The polymers have good thermal stability up to 280 °C and excellent solubility in THF. Optically transparent films were fabricated with N-ethyl-carbazole (ECZ) as a plasticizer and C60 as a charge generator. Their photorefractive performance was evaluated at 633 nm by two-beam-coupling (TBC) experiment at a zero electrical field. TBC signals were observed from these films without prepoling, indicating that the synthesized NCMC polymers bear an all-optical photorefractive property.