| Research in electro-optic materials has shown dramatic increases in the hyperpolarizablity of NLO chromophores. However, this large microscopic nonlinearity has not been translated to the bulk. The polymeric electro-optic (EO) materials continue to lack the acentric ordering of the poled chromophores within the matrix necessary for high EO response (r33). This deficiency of order represents one major obstacle that must be overcome before EO device commercialization can be achieved. The large dipole moments of high mubeta chromophores, which causes the chromophores to align in a centrosymmetric fashion through intermolecular electrostatic interactions lead to centrosymmetric ordering in the matrix thus leading to loss in activity. Thus it is important to reduce the dipole moment of the chromophores without attenuating the hyperpolarizability. Also once the chromophores have been aligned, maintaining the order is difficult owing to their electrostatic interactions and thermal motion. This dissertation will focus on engineering novel chromophore architecture, both in microscopic and macroscopic aspects in order to solve some of the aforementioned problems. Zwitterionic chromophore has been coupled with a neutral ground state chromophore in a novel design in order to decrease the dipole moment of the combined system, at the same time enhancing the hyperpolarizability. Also new polymeric systems based on the reversible Diels Alder reaction to separate the poling from the lattice hardening process, and a hyperbranched polymer system based on the CF3-FTC based chromophore have been designed and synthesized. Head-to-tail oligomers of chromophores have been synthesized so that the chromophores are pre-oriented, in an attempt to enhance poling efficiency. |
