Richard A. Minns

Cationic ring-opening photopolymerimization methods for volume hologram recording

A new photopolymer holographic recording material based on cationic ring-opening polymerization avoids limitations of conventional holographic photopolymers resulting from the free radical chemistry typically employed. The effects of oxygen, moisture, and component characteristics on holographic recording characteristics are described. Sensitivities greater than 0.1 cm2/mJ and refractive index modulations greater than 5 X 10-3 are achievable with negligible changes in the physical dimensions (volume change as low as 0.4%) of the imaged material. Linear recording is observed for exposure fluence up to 20 mJ/cm2. Good Bragg selectivity consistent with the imaged thickness is observed, and both the angular response and the diffraction efficiency are stable in these materials without the need for post-imaging fixing procedures.

Amorphous rigid-rod polymers

Synthese de tels polyamides, polyesters et polyesteramides influence de la structure moleculaire sur les proprietes optiques et morphologiques

Design and Synthesis of High Refractive Index Polymers. II

Abstract The synthesis, physical and optical properties of a series of high molecular weight, colorless, nonbirefringent, amorphous polymethacrylates (and acrylates) comprising brominated and iodinated carbazole rings that are connected to the backbone by short hydrocarbon spacers are described. The refractive indices exhibited by these homopolymers are in the range of 1.67 to 1.77. A ternary mixture of brominated monomers has a low melting point (<50°C); the refractive index of the corresponding polymer = 1.72.

High Refractive Index Polymers

Ethylenically unsaturated polymerizable acrylic (or methacrylic) monomers having pendant halogenated carbazole moieties, useful for the production of high refractive index polymers, are disclosed. The monomers are useful for the bonding of optical elements in the fabrication of optical devices.

Control of Chromophore Length in Electroluminescent Polymers. Part II. Mainchain Polymers

Abstract Electroluminescence emission has been demonstrated in mainchain polyesters and a structurally analogous polyamide. High molecular weight polyesters were synthesized by condensation of a dihydroxy functionalized, substituted, phenylene vinylene analogue, e.g., the lumo-phore, with a variety of dicarboxylic acid chlorides. The structure and hence the conjugation length of the emitting comonomer was predetermined prior to polymerization. Since the diacid moieties did not contribute to the conjugation length and hence the emission wavelength, the structure of the diacid was determined on the basis of its ease of synthesis, reactivity, and solubilizing ability in the final polymer. In each of the polyesters the electroluminescence wavelength of light-emitting diodes made from these polymers was similar to their photoluminescence emission spectrum in solution and the solid state at room temperature. The emission wavelengths ranged from blue to green. The polyamide exhibits a very broad band, nearly whi...

Consequences of chemical modification on optical and solution properties of rodlike polyamides

Abstract Rodlike polyamides were substituted to 50–55% on the nitrogen atom of the amide group with benzyl, 1-naphthylmethyl, and 4-(1,3,6,8-tetrabromo-9-carbazolyl)-1-butyl groups using a standard literature procedure. The resulting polymers exhibit significantly lower isotropic refractive indices and enhanced solubility. Polymers composed of the isophthaloyl moiety, with or without N-substitution, also exhibit lower refractive indices and enhanced solubility when compared to their rodlike analogs. These differences in properties are due to a great extent to the large difference in conformational rigidity between the two polymer types.

Synthesis of Water-Soluble Far-Red-Emitting Amphiphilic BODIPY Dyes

We report the synthesis of two water-soluble BODIPY dyes with far-red absorption and near-infrared fluorescence following cell membrane insertion. Introduction of dicationic or dianionic groups imparts water solubility and prevents translocation of the dye through the plasma membrane for highly effective labeling. The dicationic form is particularly well localized to the plasma membrane and resists quenching even after >8 min of continuous light exposure. The dyes are almost completely nonemissive in water and other highly polar solvents, but display high-fluorescence yields in chloroform and upon insertion into the extracellular leaflet.