Kyoko Hiraoka

Hydration of poly(acrylic acid) sodium salts

SummaryDrying and water uptake of poly(acrylic acid) sodium salts with different degrees of neutralization were studied. The slowing down of drying speed in solid state was not due to Tg but due to the difficulty of the release of water molecule bound to two metal carboxylates or carboxyls. The equilibrium water uptake remained almost constant below 33 % neutralization, whereas it increased linearly with neutralization beyond 33 %. This was explained by the appearance of vacant sites in octet coordination.

Hydration of poly(acrylic acid) potassium salts

SummaryDrying and water uptake of poly(acrylic acid) potassium salts with different degrees of neutralization were studied. The slowing down of drying speed in solid state was not due to Tg but due to the difficulty of the release of water molecule bound to two metal carboxylates or carboxyls. The equilibrium water uptake decreased below 25% neutralization, whereas it increased linearly with neutralization beyond 25%. The bending in the plot of equilibrium water uptake was explained by the appearance of vacant sites in bodycentered cubic coordination. The initial decrease was attributable to the sum of the two opposite effect, that is, the decrease of free carboxyl groups and the increase in dielectric nature. The results were discussed in connection with those for sodium salts described in the preceding paper.

Synthesis and fluorescence of 4-methylsulfanyl-6-pyridyl-2H-pyran-2-ones in solid state

Various 4-methylsulfanyl-6-pyridyl-2H-pyran-2-one derivatives were synthesized by the reaction of ketene dithioacetals with active methyl or methylene compounds in the presence of powdered sodium hydroxide in dimethyl sulfoxide (DMSO). Among these 2-pyrone derivatives, 3-aryl-4-methylsulfanyl-6-pyrid-2-yl-2H-pyran-2-ones show strong fluorescence in the solid state.

Syntheses and characterization of polymers containing nucleic acid bases

Abstract Two different types of polymers containing nucleic acid bases in the backbone or in the pendant groups were prepared. The polymers of the first type were polyureas obtained by the polyaddition reaction of uracil and adenine with hexamethylene diisocyanate (HMD1). The second type that is cationic polyurethanes containing nucleic acid bases in pendant groups, were obtained by the Menschutkin reaction of halogenated derivatives of uracil and adenine with a linear polyurethane containing tertiary nitrogen atoms which was based on HMD1 and N -methyldiethanolamine. Base base interactions were studied for the polymers by ultraviolet (u.r.), optical rotary dispersion (o.r.d.), and nuclear magnetic resonance (n.m.r.) spectra. A relatively high value of hypochromicity, ≈17% was observed for the mixture of the ionic polyurethane with uracil pendant and herring-sperm DNA. Complementary hydrogen bonding interactions were detected for the mixture of the ionic polyurethane with adenine pendant and with uracil pendant. The non-thrombogenic character of the polymers was examined according to the modified Lee White method. The ionic polyurethanes with adenine and uracil pendant exhibited a fairly good anti-clotting properly.