Showing papers by "David M. Collard published in 2000"
TL;DR: Palladium nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) are efficient catalysts for the Suzuki reactions in aqueous medium, suggesting that the catalytic reaction occurs on the surface of the Pd nanoparticles.
403 citations
50 citations
33 citations
TL;DR: In this paper, a poly(ethylene terephthalate) copolymers containing 2,6-anthracenedicarboxylate structural units are chain extended and crosslinked by irradiation at 350 nm.
Abstract: Poly(ethylene terephthalate) copolymers containing 2,6-anthracenedicarboxylate structural units are chain extended and cross-linked by irradiation at 350 nm. The cross-linked materials were characterized by NMR, UV−vis, DSC, and dilute solution viscometry. The cross-linking is attributed to face-to-face dimerization of the anthracene units and radical reactions. Model anthracene photodimers are cleaved in solid films of PET by irradiation at 254 nm, but polymeric anthracene photodimerization reactions are irreversible under these conditions. The combination of irreversible anthracene photodimerization and irreversible radical reactions renders the cross-links permanent.
27 citations
TL;DR: In this article, fused arenes have been prepared for use as covalently bound fluorescent optical brightening agents in condensation polymers and copolymerized with poly(ethylene terephthalate) and their optical properties are assessed.
Abstract: Diacids of fused arenes have been prepared for use as covalently bound fluorescent optical brightening agents in condensation polymers. The monomers: dimethyl 1,6-pyrene dicarboxylate, dimethyl 1,8-pyrenedicarboxylate, dimethyl 2,7-pyrenedicarboxylate, 1,8-bis(2-carboxybenzoyl)pyrene dimethyl ester, dimethyl 2,6-anthracenedicarboxylate, dimethyl 2,7-anthracenedicarboxylate and dimethyl 9,10-anthracenedicarboxylate are copolymerized with poly(ethylene terephthalate) and their optical properties are assessed. All of the polymers give blue fluorescence, with the copolymer containing dimethyl 1,6-pyrenedicarboxylate being the brightest.
17 citations
TL;DR: In this article, the fluorescence intensity of the biphenyl product in the reaction between iodobenzene and phenylboronic acid is used to determine the initial rate of the catalytic reaction.
Abstract: Palladium nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) are efficient catalysts for the Suzuki reactions in aqueous medium. The time dependence of the fluorescence intensity of the biphenyl product in the reaction between iodobenzene and phenylboronic acid is used to determine the initial rate of the catalytic reaction. The initial rate depends linearly on the concentration of Pd catalyst, suggesting that the catalytic reaction occurs on the surface of the Pd nanoparticles.
16 citations
TL;DR: In this article, the phenylene bisacrylate structural units undergo rapid photochemical reaction in the solid state to form crosslinks, which constitutes a feasible approach to polyesters, which can be photochemically thermoset after fabrication as films and fibers.
Abstract: 1,4-Phenylene bis(acrylic acid) is a thermally stable diacid, which can be incorporated into polyesters. The phenylene bisacrylate structural units undergo rapid photochemical reaction in the solid state to form crosslinks. This constitutes a feasible approach to polyesters, which can be photochemically thermoset after fabrication as films and fibers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2167–2176, 2000
11 citations
TL;DR: In this article, photo-bleach occurs in the deformation band of poly(3-octylthiophene), P3OT, using time-resolved FTIR spectroscopy (TR-FTIRS) in the nanosecond to microsecond time domain.
4 citations