Daisuke Kawaguchi

Surface mobility in polystyrene (PS) films was studied using (PS/deuterated PS) bilayer films, which were prepared by attaching original two surfaces together. Time evolution of the bilayer interface at various temperatures was examined by dynamic secondary ion mass spectroscopy in conjunction with neutron reflectivity. When the bilayer was annealed at a temperature above bulk glass transition temperature, Tgb, the interfacial thickening was well expressed by the context of Fickian diffusion. On

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTComparison of Interdiffusion Behavior between Cyclic and Linear Polystyrenes with High Molecular WeightsDaisuke Kawaguchi, Keisuke Masuoka, Atsushi Takano, Keiji Tanaka, Toshihiko Nagamura, Naoya Torikai, Robert M. Dalgliesh, Sean Langridge, and Yushu MatsushitaView Author Information Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japa

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSurface Mobile Layer of Polystyrene Film below Bulk Glass Transition TemperatureDaisuke Kawaguchi, Keiji Tanaka, Atsushi Takahara, and Tisato KajiyamaView Author Information Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Fukuoka 812-8581, Japan Cite this: Macromolecules 2001, 34, 18, 6164–6166Publication Date (Web):July 31, 2001Publication History Received2 January 2001Revised7 May

Partially quaternized poly(4-vinylpyridine) (P4VP) gels were prepared by irradiating aqueous solutions with γ-rays. Swelling degrees in water increased with increasing the degree of quaternization (charge density) except for gels of I- or SCN- counterions, while those in mixed solvents (water/methanol, ethanol, 2-propanol, dimethyl sulfoxide, acetone, or dioxane) decreased with increasing the charge density and/or with decreasing the dielectric constant of the mixed solvent. This trend was more

Messenger RNAs (mRNAs) with phosphorothioate modification (PS-mRNA) to the phosphate site of A, G, C, and U with all 16 possible combinations were prepared, and the translation reaction was evaluated using an E. coli cell-free translation system. Protein synthesis from PS-mRNA increased in 12 of 15 patterns when compared with that of unmodified mRNA. The protein yield increased 22-fold when the phosphorothioate modification at A/C sites was introduced into the region from the 5'-end to the initi

Surface aggregation states in miscible blends of monodisperse polystyrene (PS) and poly(vinyl methyl ether) (PVME) were studied by X-ray photoelectron spectroscopy (XPS) in conjunction with neutron reflectivity (NR). In the case of symmetric blends in terms of degree of polymerization, N, PVME and PS were preferentially segregated at the film surface and the interface with a silicon wafer, respectively, to minimize free energy of the system. The concentration profile near the surface obtained by

Proton conductivity of polyelectrolytes in the interfacial region with a solid is key to the performance of polyelectrolyte-based fuel cells. The proton conductivity of Nafion thin films was examined as a function of the thickness along both directions, normal and parallel to the interface. Neutron reflectivity measurements revealed that a water-containing multilamellar structure was formed at the substrate interface. The presence of the interfacial layer, or the two-dimensional proton-conductiv

The effect of chain-end chemistry on surface and interfacial segregation in symmetric blends of polystyrene (hPS)/deuterated polystyrene (dPS) has been investigated by X-ray photoelectron and secondary ion mass spectroscopy in conjunction with neutron reflectivity measurements. Alpha,omega-fluoroalkyl- and alpha,omega-carboxy-terminated polystyrenes (alpha,omega-hPS(Rf)2 and alpha,omega-hPS(COOH)2) were used as end-functionalized polymers; the former possesses chain ends with lower surface energ

The short-time mutual diffusion at an interface of linear polystyrene/linear deuterated polystyrene with different molecular weights was examined by time-resolved neutron reflectivity (TR-NR) measurements. The model scattering length density (b/V) profiles obtained by solving a partial differential equation for the diffusion process, using the segmental diffusion coefficients as the only fitting parameter were used to analyze the TR-NR data. In short-time diffusion, the asymmetric (b/V) profiles

The direct acetalization of ethanol is a significant challenge for upgrading bioethanol to value-added chemicals. In this study, 1,1-diethoxyethane (DEE) is selectively synthesized by the electrolysis of ethanol using a proton-exchange membrane (PEM) reactor. In the PEM reactor, a Pt/C catalyst promoted the electro-oxidation of ethanol to acetaldehyde. The Nafion membrane used as the PEM served as a solid acid catalyst for the acetalization of ethanol and electrochemically formed acetaldehyde. D