Keisuke Watanabe

• Ph.D
• Professor (Assistant) at Fukuoka University

Affinity analysis using Hansen solubility parameters (HSP) reveals that the gel-sol transition point of binary organogels is correlated with preferential interactions between the solvophilic moiety of gelators and solvents. The decomposition of gelators in HSP analysis can be effectively used for predicting the thermal stability of gels.

The relationship between dehydration of polymer chains and the nanodroplet formation through the macroscopic liquid-liquid phase separation (LLPS) has been investigated for the aqueous solution of stereocontrolled poly(N-isopropylacrylamide) (PNiPAm) and poly(N-diethylacrylamide) (PNdEAm). The fluorescent probe method reveals that the temperature r...

Mixtures of the ionic liquids 1-methyl-3-octylimidazolium phenylazophenolate, abbreviated as [C8mim][AzoO] and 1-methyl-3-octylimidazolium hexafluorophosphate, abbreviated as [C8mim][PF6], have been known as smart materials with high moldability, electric conductivity, and self-healing properties. However, the structure and the phase behavior at lo...

The room temperature ionic liquid, 1-methyl-3-octylimidazolium tetrafluoroborate, abbreviated as [C8mim]BF4, has been known as a good glass-former, which can be cooled or heated at normal scanning rates without any phase transition. However, after cooling to 183 K, just below the glass transition temperature, 190 K, followed by heating to 223 K, Tg...

A poly(ethylene oxide) (PEO)–poly(propylene oxide) (PPO) alternating multiblock (AMB) copolymer with various molecular weights was prepared via precipitation fractionation from an acetone/n‐hexane mixture. The cloud point (Tc) of the aqueous solution of PEO–PPO AMB copolymer decreased as the number‐average molecular weight of the sample increased....

The mobility, thermal behaviour, and crystal structures of water molecules confined within a one‐dimensional (1‐D), nanoporous single crystal in the premelting state were investigated in this study. Water clusters confined within the hydrophilic crystal revealed a premelting phase that was intermediate between the frozen and melted states. Water mo...

Glass-transition behavior of hydrated bovine serum albumin (BSA) aqueous solutions depending on hydration degree within 0.05 and 0.43 h (water-g/protein-g) was investigated according to the measurement of an enthalpy-relaxation rate deduced from the temperature drift observed by adiabatic calorimetry. The results showed that an increase in hydratio...

Effects of the stereoregularity on the hysteresis in demixing and remixing of the aqueous solution of poly(N-isopropylacrylamide) (PNiPAm) observed as the dissociation of transmittance curves in heating and cooling have been studied. For the liquid-liquid phase separation of the monomer model (N-isopropyl propionamide)/water binary mixture, no hyst...

The micellization behaviors of two types of the poly(ethylene oxide) (PEO) - poly(propylene oxide) (PPO) alternating multiblock (AMB) copolymers in water, which have a different weight fraction of PEO (fPEO), have been investigated. Surface tension measurements reveal that the molecular area at air/water interface of the PEO-PPO AMB copolymers is s...

Thermal changes in the association behavior of poly(ethylene oxide)–poly(propylene oxide) alternating multiblock (PEO–PPO AMB) copolymers in water are investigated by the use of transmittance and light scattering measurements. Two PEO–PPO AMB copolymers with a different weight fraction of PEO, (EO220PO33)8 and (EO68PO33)9, are prepared. The weight-...

Water molecule is very simple in its structure and tends to form tetrahedrally arranged hydrogen bonds with other molecules. Bulk water inevitably crystallizes without being supercooled over 235 K even in a droplet with a diameter of µm. Water confined within nm spaces, being abundantly present on the earth, behaves differently from the bulk one. I...

Thermal properties of channel water within crystalline nanopores of [M(H 2 bim) 3 ](TMA)·nH 2 O (M = Co, Ru) were characterized by adiabatic calorimetry, where H 2 bim and TMA denote 2,2′-biimidazole and 1,3,5-benzenetricarboxylic acid, respectively. Temperature dependence of the heat capacities and spontaneous heat release or absorption rates disc...

The thermal properties of crystalline complex [Cr(H(2)bim)(3)](TMA) x 23.5 H(2)O were studied by adiabatic calorimetry to clarify the structural ordering and dynamic freezing-in behaviors of the nanochannel water within the pores possessing crystalline wall structure, where H(2)bim denotes 2,2'-biimidazole and TMA is 1,3,5-benzenetricarboxylic acid...

Adiabatic calorimetry was carried out for Na(H)-RUB-18 crystals with and without the water confined between the silicate layers. The hydrated sample was prepared by allowing the Na cations of Na-RUB-18 to be ion-exchanged in a 0.2 moldm-3 HCl aqueous solution. A heat-capacity peak was found at 194 K and two glass transitions at Tg = 96 K and 130 K...

The behavior of the water accommodated between the silicate layers of a clay Na8 [Si32O64(OH)8]̇32H 2O was investigated by using adiabatic calorimetry. A phase transition was observed showing a heat-capacity peak at 194 K and its entropy was roughly estimated to be 5.2 JK-1 (H2O-mol) -1. The transition was interpreted to be essentially due to an or...

Heat capacities and enthalpy relaxation rates were measured for crystalline [Ni(cyclam)(H2O)2]3(TMA)224H2O, where cyclam is 1,4,8,11-tetraazacyclotetradecane, TMA is 1,3,5-benzene tricarboxylic acid, and 24H2O represents the water forming a nano-channel. A phase transition was found to occur at 196.9 K, and a glass transition at 87 K. A potential p...

Low-temperature thermal properties of crystalline [Co(H(2)bim)(3)](TMA)·20H(2)O were studied by adiabatic calorimetry, where H(2)bim is 2,2'-biimidazole, TMA is 1,3,5-benzene tricarboxylic acid, and 20H(2)O represents the water forming nano-channel in the crystal. A glass transition was observed at T(g) = 107 K. It was discussed as a freezing-in ph...