Synthesis and electro-optic properties of the chromophore-containing NLO polyarylate polymers

Base on the same two monomers, diphenolic acid (DPA) and isophthaloyl chloride (IPC), three chromophore-containing nonlinear optical (NLO) polyarylate polymers were prepared. A tricyanofuran (TCF)-acceptor type chromophore group was in main-chain (mPAR-chr1), side-chain (sPAR-chr1) and side-chain with a 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane (BPAPF) group (sPAR-F-chr1), respectively. The obtained polymers were characterized and evaluated by UV-Vis, ¹H NMR, DSC and TGA. All the polymers exhibited good electro-optic (EO) activity. The relationship between EO coefficients (r₃₃) and the chromophore concentration of the three polymers were also characterized and discussed. There were no obvious differences found in EO activity between mPAR-chr1 and sPAR-chr1 polyarylates with the same chromophore. The fluorinated block polyarylate sPAR-F-chr1 has the largest r₃₃ value in these three polyarylates which is 52 pm/V at the wavelength of 1310 nm (which is almost twice the r₃₃ value of normal polymers contained the same chormophore at the same content), when the concentration of chromophore 1 is 18wt.%. 85% of the r₃₃ value was retained in the sPAR-F-chr1 after being heated at 85°C for 600 hours. The polymer sPAR-F-chr1, with good solubility, high T_g (above 200 °C) and side functional group at the same time, may probably be a practical NLO material. These properties make the new polyarylates have potential applications in EO devices such as EO modulators and switches.