title: Synthesis and characterization of ethylene glycol substituted poly(phenylene vinylene) derivatives.
abstract: We report the synthesis of a series of water-soluble, fluorescent, conjugated polymers via the Gilch reaction with an overall yield greater than 40%. The yield for the Gilch reaction decreases with the increase in the length of the side chain (ethylene glycol repeat units), presumably due to the steric effects inhibiting the linking of monomeric units. The hydrophilic side chain enhances the solubility of the polymer in water and concomitantly leads to a side-chain-dependent conformation and solvent-dependent quantum efficiency. An increase in the ethylene glycol repeat units on the polymer side chain structure results in changes in chain packing; hence, the crystallinity evolves from semicrystalline to liquid crystalline to completely amorphous. An increase in the length of the side chain leads to changes in the polymer-solvent interaction as manifested in the photophysical properties of these polymers. These novel polymers exhibit two glass transition temperatures, which can be readily rationalized by differences in microstructure when casted from hydrophobic and hydrophilic solvents. Cyclic voltammograms of polymer 1d-3d suggest two-electron transfer, as compared to P1 which has one complete redox pair. The potential of having a nanoscaled domain structure and stabilizing two electrons on a polymer chain signifies the potential of these polymers in fabricating electronic and photovoltaic devices.
authors.affiliation: Physical Chemistry and Applied Spectroscopy, Chemistry Division, Los Alamos National Laboratory, Mail Stop J567, Los Alamos, New Mexico 87545.
authors.forename: Chun-Chih
authors.initials: CC
authors.lastname: Wang
authors.forename: Hsinhan
authors.initials: H
authors.lastname: Tsai
authors.forename: Hung-Hsin
authors.initials: HH
authors.lastname: Shih
authors.forename: Seaho
authors.initials: S
authors.lastname: Jeon
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Xu
authors.forename: Darrick
authors.initials: D
authors.lastname: Williams
authors.forename: Srinivas
authors.initials: S
authors.lastname: Iyer
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Sanchez
authors.forename: Leeyih
authors.initials: L
authors.lastname: Wang
authors.forename: Mircea
authors.initials: M
authors.lastname: Cotlet
authors.forename: Hsing-Lin
authors.initials: HL
authors.lastname: Wang