High stability poly(N-adamantyl-exo-norbornene-5,6-dicarboximide) and phenyl vinylene thiophene electro-optic host-guest system

Poly(N-adamantyl-exo-norbornene-5,6-dicarboximide) was prepared by ring opening metathesis polymerization. This was achieved in chloroform using the Grubbs 1st generation initiator and quenched with ethyl vinyl ether. The polymer had a weight average molecular weight of 27,000 g/mol with a polydispersity index of 2.19, a high glass transition temperature of 281 °C and a high thermal decomposition temperature of 385 °C (10% loss). The trans:cis vinylene ratio was 1.00:0.19 making the polymer amorphous. The polymer was used as a host for 5 guest nonlinear optical chromophores. The relationship between the chromophore structure and the electro-optic coefficient was investigated. A range of chromophore concentrations were evaluated and it was found that the ideal chromophore structure included a bulky tert-butyldiphenylsilane side group. A maximum r₃₃ of 80 pm/V was obtained at a chromophore concentration of 45 wt% and a poling temperature of 160 °C. A host-guest system containing 35 wt% of the tert-butyldiphenylsilane substituted chromophore had a stability of 85% at a temperature of 85 °C for 500 h. The stability at 105 °C was 72%. In comparison amorphous polycarbonate under the same conditions achieved a stability of just 58% at 85 °C, while poly(methyl methacrylate) had a stability of 0% at 85 °C.