Toru Ishidao

Swelling equilibria of poly(N-isopropylacrylamide) gel in aqueous polymer solutions

Abstract Swelling equilibria of poly(N-isopropylacrylamide) (NIPA) gel in poly (ethylene glycol) (PEG)-water mixtures and the concentrations of PEG inside and outside the NIPA gel at 298.2K are discussed. NIPA gel exhibited continuous deswelling behavior for PEG6000, 20000, and 50000, a volume phase transition for PEG 1000, and reentrant behavior for PEG200. From the partition of PEG, it was found that the PEG molecules could not penetrate into the gel network in shrunk state. The gel absorbed low molecular weight PEGs but excluded high molecular weight PEGs in swollen state. A thermodynamic model, based on the Flory-Huggins theory coupled with the osmotic pressure by rubber elasticity proposed by Flory, was applied to correlate the swelling behavior of the gel in PEG-water mixtures.

Solvent concentrations of dimethylsulfoxide-water and 1-propanol-water solutions inside and outside poly (N-isopropylacrylamide) gel

The volumes of poly (N-isopropylacrylamide) (NIPA) gel in both dimethylsulfoxide (DMSO)-water and 1-propanol-water solutions were measured at 25°C. The solvent concentrations inside and outside the NIPA gel were also measured. The gel was swollen in water, shrunk according to increase in concentration of organic solvent, and reswollen in pure organic solvent. This phenomenon is typical reentrant swelling behavior. The DMSO concentrations inside the gel were almost equal to those outside the gel in the whole concentration range. On the other hand, the 1-propanol concentrations between inside and outside the gel were much different from each other in the shrunk state, though they were almost the same in the swollen state.

Solubilities of nonane vapor in styrene-butadiene copolymers at 100 and 130° C

Abstract Iwai, Y., Ishidao, T., Miyamoto, S., Ikeda, H. and Arai, Y., 1991. Solubilities of nonane vapor in styrene-butadiene copolymers at 100 and 130 °C. Fluid Phase Equilibria 68: 197-205. The solubilities of nonane vapor in styrene-butadiene copolymers were measured with a sorption apparatus at 100 and 130 ° C for mass fractions of nonane ranging from 0 to 0.17. It is shown that the UNIFAC-FV model can be applied to predict the solubilities of nonane in styrene-butadiene copolymers.

Swelling equilibria of poly(N-isopropylacrylamide) gel in glucose and starch aqueous solution

Abstract Swelling equilibria of poly(N-isopropylacrylamide) (NIPA) gel in starch–water and glucose–water aqueous solutions were measured at 20, 25, 30 and 33°C. Furthermore, solvent concentrations inside and outside the gel were measured at 20°C. The gel exhibited continuous deswelling behavior in starch–water aqueous solution. A large amount of starch could hardly penetrate into the gel network. On the other hand, a volume phase transition of the gel was observed in glucose–water aqueous solution. A significant amount of glucose could penetrate into the gel network. A solution model, based on the Flory–Huggins formula coupled with osmotic pressure by rubber elasticity proposed by Flory, was adopted to correlate the phase behavior of the gel in starch–water and glucose–water aqueous solutions. The volume change behavior and the equilibrium concentrations inside and outside the gel were successfully correlated by using the model.

Estimation of solid molar volumes using the neighboring factor with application to isomeric compounds

We examine a new approach to estimate the solid molar volumes of aromatic compounds using a neighboring factor, which relates to the difference in size between two neighboring groups