Kenichi Izawa

2D gel permeation chromatography (2D GPC) correlation studies of the growth process for perfluoro-octyltriethoxysilane polymer aggregates

A novel analytical technique, two-dimensional correlation gel permeation chromatography (2D correlation GPC), has been used to elucidate intricate details of the two-step (I and II) polymerization of 1H,1H,2H,2H-perfluoro-octyltriethoxysilane (PFOTES) catalyzed by 0.5, 1.0 and 2.0 M HCl·H2O over a time period of 600–14 400 s. The 2D GPC correlation results demonstrate that each elution band (particularly, in step II) consists of two (reactive and nonreactive) components and that a higher HCl concentration enhances the correlation of the reactive component with other bands. It is suggested that rapid growth of the polymeric aggregates in step II may be caused by the appearance of these reactive components.

Application of generalized two-dimensional correlation theory to gel permeation chromatographic analysis

This report demonstrates the promising potential for the application of generalized two-dimensional correlation analysis to time dependent GPC elution profiles, in analysis of complex dynamic variations in the sol–gel polymerization process.

Concentration-resolved 2D correlation gel permeation chromatography study of aggregate-aggregate interactions in the polymerization products of triethoxysilyl-terminated polystyrene silane-coupling agent.

Concentration-resolved 2D correlation gel permeation chromatography (GPC) has been used to examine the intricate details of the HCl-catalyzed polymerization of a polymeric silane-coupling agent (SCA), triethoxysilyl-terminated polystyrene (TESiPS). The concentration-resolved 2D correlation GPC maps directly reflect the marked difference in the aggregate-aggregate interactions of dilute and concentrated monomeric units, which govern the differences in the polymerized products. There is an optimum concentration of SCA for the enhancement of interfacial strength and subsequent polymerization. Thus, the concentration-resolved 2D correlation GPC technique can be used as a powerful tool for elucidation of aggregate-aggregate interactions and reaction mechanisms in a surface- or interface-enhanced reaction system. It has been shown that the yield value of polymerization products can be improved to a marked extent by choosing a high initial monomer concentration, due to the increase in the production of oligomers. Multiple reaction processes are promoted by the self-assembly of the monomeric and oligomeric components.

Two-dimensional correlation gel permeation chromatography (2D correlation GPC) study of the sol–gel polymerization of octyltriethoxysilane. HCl-concentration dependence

Two-dimensional correlation gel permeation chromatography (2D GPC) was used to elucidate intricate details of the initial ten minutes of the sol–gel transition of n-octyltriethoxysilane (OTES), catalysed by 0.5 and 2.0 M HCl·H 2 O. The results demonstrate that the features of 2D GPC correlation spectra directly reflect the dynamic variation of reactions or interactions present during the polymerization process.

Complex, Dynamic Behavior of Extremely Asymmetric Di-n-Alkylphosphate-Anion Aggregates, the Long-Chain Effect and the Role of a Limiting Size: Cryo-TEM, SANS, and X-Ray Diffraction Studies

For extremely asymmetric n-hexyl(n-decyl)phosphate (HDeP), n-hexyl(n-dodecyl)phosphate (HDoP), and n-hexyl(n-cetyl)phosphate (HCeP), the effect of the long-chains on the dynamic behavior of their aggregate structures in water was examined by cryo-TEM imaging, SANS, and X-ray diffraction techniques. The cryo-TEM images demonstrated the complex and dynamic behavior of the aggregates, and its dependence on the length of the long-chain. Application of the one-dimensional aggregate theory to the SANS results led to the conclusion that the existence of a limiting size also depended on the length of the main long-hydrocarbon chain and affected strongly the dynamic behavior of the aggregates, causing breakage of thread-like micelles or ribbon-like aggregates. The X-ray diffraction patterns of the lyotropic liquid crystalline samples of HDeP and HCeP were used to estimate the aggregate structures of this limited size.