THE ROLES OF REACTION INHOMOGENEITY IN PHASE SEPARATION KINETICS AND MORPHOLOGY OF REACTIVE POLYMER BLENDS

The roles of reaction inhomogeneity in phase separation of polymer mixtures were described and summarized via two examples:photocross-link of polymer mixtures in the bulk state and photopolymerization of monomer in the liquid state. The reaction kinetics,the reaction-induced elastic strain and the phase separation kinetics were monitored respectively by UV-Vis spectroscopy,Mach-Zehnder interferometry and laser-scanning confocal microscopy.It was found that phase separation in the bulk state was strongly ...     

Single-walled carbon nanotubes acquire a specific lectin-affinity through supramolecular wrapping with lactose-appended schizophyllan

Single-walled carbon nanotubes can be entrapped within a helical superstructure composed of schizophyllan bearing lactoside-appendages to show an excellent water-solubility as well as a specific lectin-affinity.     

Nanocrystals Assembled by the Chemical Reaction of the Dispersion Solvent

The development of methods to pattern nanocrystals with different sizes and shapes remains a challenge. In this study, we demonstrate a unique class of bottom‐up approaches to assemble nanocrystals into patterns. Our approach for patterning nanocrystals focuses on the utilization and control of the chemical reaction of solvents surrounding nanocrystals. The photopolymerization of solvent molecules through a photomask creates time‐dependent concentration gradients of the solvents. Dispersed nanocrystals such as silver nanowires (AgNWs) migrate and are gradually organized and integrated into the polymerizing films based on the concentration gradients. The AgNW‐embedded film properties are determined by the organized AgNW structures and include light transmission and electrical conductivity. Overall, the demonstrated method is very simple, widely applicable to various nanocrystals and solvents, and can thus contribute to the development of a new class of nanocrystal patterning methods.     

Adsorption behavior of lauric acid at heptane/water interface as studied by second harmonic generation spectroscopy and interfacial tensiometry.

Interfacial tensiometry and second harmonic generation (SHG) spectroscopy were applied to examine the adsorption behavior of lauric acid (LA) at a heptane/water interface. From interfacial tensiometry measurements, the adsorption kinetics of LA was revealed to be diffusion-controlled, and the adsorption constant of LA was estimated to be 9.6 x 10(4) M(-1). The adsorption isotherms obtained by SHG measurements were analyzed by taking account of both the molecular orientation of LA at the interface and a surface electric field generated by the adsorbed LA layer. It was confirmed that the carboxylic groups of adsorbed LA molecules were well ordered at the heptane/water interface and the orientation of the carboxylate group was invariant during the adsorption process.     

Interactions of counterions with dextran sulfate in aqueous solutions

Counterion activity coefficients in solutions of dextran sulfate with and without added salts were determined potentiometrically by using a cation-exchange membrane and a sodium glass electrode. Dextran sulfate was shown to interact with monovalent cations in the order of preference: K⁺ > Cs⁺ > Na⁺ > Li⁺, whereas no specificity was found for bivalent cations. On the basis of light-scattering measurements, the expansion of the dextran sulfate polyion in solutions of alkali metal salts was found to fall in the same order as the counterion activity coefficients in salt-free solutions. It was also shown that the dextran sulfate polyion assumes a more extended conformation in magnesium chloride solution than in calcium chloride. These results were substantiated by measurements of solution viscosities.     

Synthesis and regioselective N- and O-alkylation of 3-alkyl-5-phenyl-3H-[1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-ones and 2-phenyl-9-propyl-9H-purin-6(1H)-one with evaluation of antiviral and antitumor activities

3-Alkyl-5-phenyl-3H-[1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-ones were prepared by nitrosative cyclization of the appropriate 5,6-diamino-2-phenylpyrimidin-4(3H)-ones with nitrous acid and were subjected to regioselective alkylation with several alkylating agents in aprotic solvent at different temperature. Simultaneous 6-N- and 7-O-alkylation were observed and the regioselectivity varied remarkably with size and shape of the alkylating agents as well as with the reaction temperature. Similarly, N- and O-alkylation as well as selectivity was also observed in the case of 2-phenyl-9-propyl-9H-purin-6(1H)-one. Some of the synthesized compounds showed moderate antiviral and antitumor activities.