Synthesis of poly vinyl ethers with pendant non-linear optical azo dyes

Two vinyl ether polymers with pendant 4′-amino-4-nitroazobenzene dyes were synthesized with different lengths of spacer from the main chain. The synthesis involved polymerization of 2-chloroethylvinyl ether with HI/I 2 to give a polymer of M n 13200 and M w/M n 1.23. The azo-dye molecules were attached to this polymer backbone by a Williamson ether synthesis route using a propyl or hexyl alcohol derivative of the azo dye. High loading of the dyes (> 75%) was achieved as measured by visible spectrophotometry, elemental analysis and 1H-NMR. The polymers exhibit high solubility in a range of solvents and thermal stability up to 200° in air. Liquid crystal (nematic) behaviour is observed for these polymers on cooling from the isotropic melt phase.