Photosensitization of bioinspired thymine-containing polymers.

Here, we report a sensitization study on a family of water-soluble photopolymers based on thymine. The goal of this study was to determine whether the presence of sensitizer molecules would promote photocrosslinking/immobilization of the polymers using low-energy irradiation (520 nm) as compared to the UV irradiation (approximately 280 nm) necessary for the standard photoinduced process to take place. With the aid of Eosin Y Spirit Soluble (EY) as a sensitizer, water-soluble polystyrene copolymers of vinylbenzylthymine-vinylbenzyltriethylammonium chloride (VBT-VBA) were immobilized after exposure to visible irradiation.

Effect of pH on the viscosity of titanium dioxide aqueous dispersions with carboxylic acids.

Dispersions of titanium dioxide nanoparticles with terephthalic acid, isophthalic acid, salicylic acid, benzoic acid, and pyridine-2,5-dicarboxylic acid were prepared by aqueous grinding. The pH of the dispersions was adjusted by adding either HCl or NaOH, and the viscosity of the dispersions was measured. It was found that the viscosity of the system depends strongly on pH.

OH, HO2, and ozone gaseous diffusion coefficients.

The diffusion of OH, HO2, and O3 in He, and of OH in air, has been investigated using a coated-wall flow tube reactor coupled to a chemical ionization mass spectrometry. The diffusion coefficients were determined from measurements of the loss of the reactive species to the flow tube wall as a function of pressure. On the basis of the experimental results, D(OH-He) = 662 +/- 33 Torr cm2 s-1, D(OH-air) = 165 +/- 20 Torr cm2 s-1, D(HO2-He) = 430 +/- 30 Torr cm2 s-1, and D(O3-He) = 410 +/- 25 Torr cm2 s-1 at 296 K.

Photo-cross-linked immobilization of polyelectrolytes for enzymatic construction of conductive nanocomposites.

Horseradish peroxidase has been demonstrated to catalyze the oxidative polymerization of aniline to form conductive polyaniline. This process is facilitated by the presence of a macromolecular template with sulfonic acid groups that provide a unique environment for the formation of the conducting polymer. Here we report the use of a photo-cross-linkable thymine-based polymer with phenylsulfonate groups as a templating substrate.