Adsolubilization of 2-naphthol into adsorbed layer of PEO-PPO-PEO triblock copolymers on hydrophilic silica

Adsolubilization of 2-naphthol into an adsorbed layer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers (Pluronics) on hydrophilic silica has been investigated. Four kinds of Pluronics (P103, P105, P123, and F108) were used in order to understand the effect of the hydrophobicity of surfactant on the adsolubilization. The order of the adsorption in the saturation level was found to be P123 approximately P103 > P105 > F108, meaning that Pluronics with higher hydrophobicity can adsorb preferentially to the silica surface. Indeed, this order was parallel to the order of the adsolubilization amount of 2-naphthol. In the case of co-addition of the Pluronics and 2-naphthol, the adsolubilization amount increased gradually at lower surfactant concentration regions, reached a maximum, and then decreased with increasing concentration of the Pluronics. The maximum amount appeared at critical polymolecular micelle concentration of each Pluronics. On the other hand, the final decrement was not observed when 2-naphthol was added after replacement of the Pluronics supernatant by the Pluronics free solution. These results suggest that adsolubilization behavior is influenced by the existence of the polymolecular micellar aggregates in the solution phase.     

Cycloaddition reaction of schiff bases with ketenes generated by pyrolysis of 2‐aryl‐substituted 1,5,7‐trioxaspiro[2.5]octane‐4,8‐diones

The α‐oxo ketenes 6 which are generated by the pyrolysis of the 2‐aryl‐substituted 1,5,7‐trioxaspiro[2.5]octane‐4,8‐diones 1 , were reacted with Schiff bases 2 to give spiro compounds constructed between the β‐lactam and 1,3‐dioxolan‐4‐one; i.e., the 2,3,6‐triaryl‐2‐aza‐5,7‐dioxaspiro[3.4]octane‐1,8‐diones 3 and 4 . Hydrogenation of the mixture of 3a and 4a in the presence of catalytic amount of Pd‐C produced the trans‐2‐benzyloxy‐1,4‐diphenyl‐β‐lactam‐3‐carboxylic acid 9 .     

1D helical polymeric chain with a pseudo-5(3) screw axis formed by cuprophilicity. synthesis and crystal structure of copper(I) pivalate

A coordination polymer, [Cu5(piv)5]n (piv = pivalate), was prepared by a thermal decomposition method. The unit cell of the crystal structure consisted of one right-handed helical chain and one left-handed helical chain, which were formed by an alternation of Cu(I) ions and carboxylate (O-C-O) groups. This chain possessed a pseudo-5(3) screw axis; the second-order structure was suggested to be realized by a balance between the cuprophilicity and a steric effect of the tert-butyl groups.     

Morphology of poly(p‐oxybenzoyl) prepared in perfluoropolyether

Solvent effect on the morphology of poly(p‐oxybenzoyl) (POB) prepared by the reaction‐induced phase separation of oligomers was examined by the polymerization of p‐acetoxybenzoic acid in perfluoropolyether Aflunox^TM (AFL2507 and AFL606). Polymerization was carried out at 320°C for 6 hr. POB microspheres were formed in AFL2507 by the liquid–liquid phase separation of oligomers due to the low miscibility of oligomers in AFL2507. The molecular weight of the solvent influenced the morphology, and the polymerization in AFL606 of which the molecular weight was lower than AFL2507 yielded whiskers formed by crystallization of oligomers induced by the increase in miscibility compared with that in AFL2507. The solvent structure and its molecular weight influenced the miscibility of oligomers and ultimately controlled the morphology from whisker to microsphere. Copyright © 2004 John Wiley & Sons, Ltd.     

Characterization of silica-coated hematite and application to the formation of composite particles including egg yolk PC liposomes

According to the method of Ohmori et al. (J. Colloid Interface Sci. 150 (1992) 594), a procedure is examined for the buildup of uniform silica layers on monodispersed hematite particles. It appears that the silica layer resulting is homogeneous and the layer thickness is controlled by the concentration of tetraethylorthosilicate (TEOS) in the medium. Further, egg PC liposomes, a typical biocolloid, are introduced onto the silica-coated hematite particle. The formation was proceeded by two types of processes: (1) heterocoagulation between the silica-coated hematite and egg PC liposomes by controlling the concentration of LaCl(3) in the medium, or (2) buildup using two proteins (lysozyme or cytochrome C) as binder molecules. These results were analyzed by zeta-potential measurements and a contact-type X-ray microscope, which is a unique technique for obtaining X-ray images of biological specimens in water with high resolution.     

Far-infrared spectra of some β-hydroquinone clathrates

Far-infrared spectra (400-30 cm^?1) of Nujol mulls of the β-hydroquinone clathrates containing the following guest molecules were investigated: formic acid, formic acid-d₂, methanol, methanol-d₄, acetonitrile, acetonitrile-d₃, sulphur dioxide and also both of methanol and sulphur dioxide. The observed infrared bands of the mulls in the region of 4000-30 cm^?1 were classified into those due to the host lattice and those due to the guest molecules. On the basis of the comparison of the spectra, some bands were assigned to the translational or the rotational vibrations of guest molecules. Appearance of those bands suggested that some guest molecules are considerably bound in the cavities of the host lattice. Effect of temperature change on the bands was also measured.     

Accurate and rapid estimation on spectral interferences in routine analysis by ICP-AES: use of mutual interference coefficients

A practical method to estimate spectral interferences and to select optimum analytical lines in ICP-AES is suggested. Depending on the matrix composition and the amounts of the analyte, the analytical lines suffering from little interferences and the limit of determination can be determined from calculation using spectral interference coefficients. For this calculation, the spectral interference coefficients, which are defined as apparent mass of the analyte equivalent to the spectral interference from unit mass of the interferent, are obtained experimentally for 639 emission lines of 68 elements. There is a good correlation between the coefficients obtained on two spectrometers having different resolutions. Received: 24 June 1997 / Revised: 4 December 1997 / Accepted: 24 January 1998     

Agitation effect on the rate of soapless emulsion polymerization of methyl methacrylate in water

In order to identify the factors causing an agitation effect on the rate of soapless emulsion polymerization, the polymerization of methyl methacrylate was carried out in water. Experimental results indicated the significance of monomer transfer from monomer droplets to water. A kinetic model was proposed which would take into account this monomer transfer. This model enabled the effect of monomer transfer on the rate of soapless emulsion polymerization to be evaluated for the present system and the experimental results to be interpreted qualitatively.