A modular approach for making second-order nonlinear optical (NLO) side-chain aromatic polyquinolines has been developed. The synthesis provides a method for readily incorporating NLO chromophores into the pendent phenyl moieties of parent polyquinolines at the final stage via the Mitsunobu reaction. The method produces polyquinolines with a wide range of polymer backbones and offers great flexibility in the selection of NLO chromophores. These side-chain NLO polyquinolines demonstrate high electro-optic (E-O) activities (up to 35 pm/V at 830 nm and 22 pm/V at 1300 nm) and excellent tradeoffs among thermal, optical, and electrical properties.

Most recently, a series of novel second-order NLO thermoset polymers containing silicon-perfluorocyclobutane (PFCB) has also been synthesized. This was accomplished via the crosslinking reaction between the di(trifluorovinylether)-containing NLO chromophores and the tris(trifluorovinylether) monomer in solid state at 180-250 °C. The radical-mediated, stepwise cycloaddition reaction offers great tolerance to very sensitive functional groups such as tricyanovinyl acceptor. A variety of NLO chromophores could be easily incorporated into these thermoset polymers compared to the modular approach. Preliminary results have indicated these polymers to possess excellent processability, low optical loss, and a combination of highly desirable thermal, nonlinear optical, and mechanical properties.

A series of cyano-containing distyrylbenzenes which have the electron-withdrawing groups functionalized on the central phenylene ring were synthesized via the Wittig-Horner reaction. Electrochemical study showed that the electron-affinity of these molecules increased with the increasing strength of electron-accepting groups. 1,4-Bis(4'- t-Butylstyryl)-2,5-bis(dicyanovinyl)benzene (6) possessed a low LUMO energy level at -4.01 eV, which provided a better match to the work function of Al cathode. Compared to the cyano-terephthalylidene (2), introducing cyano groups on the aromatic ring (3) instead of on the vinylene linkage provided better stabilization to the radical anions. The emission colors spanning green, yellow, orange, red could be achieved by changing the electron-accepting strength of oligophenylenevinylenes (3-6). Energy gap reductions were caused by a stronger decrease of the LUMO energies than the HOMO energies. These results provided new insights for the design of suitable polymers with much improved electron affinities facilitating electron injection from higher work function metal electrodes.