Hanako Asai

High-performance ion gel with tetra-PEG network

In this paper, we show a free-standing highly ion-conducting ionic liquid (IL)-polymer electrolyte, Tetra-PEG ion gel, prepared by incorporating imidazolium-based ILs into very much lower concentration (3–6 wt%) of tetra-arm poly(ethylene glycol), Tetra-PEG. The ionic conductivities of the free-standing Tetra-PEG ion gels were nearly equal to those of pure ILs, indicating a realization of liquid-like conductivity in a solid-state material. The Tetra-PEG ion gels showed advanced mechanical properties demonstrated by the results of compression and stretching tests.

Thoroughly mesoporous TiO2 nanotubes prepared by a foaming agent-assisted electrospun template for photocatalytic applications

A thoroughly mesoporous long TiO2 nanotube with intact morphology was firstly prepared using a foaming agent-assisted electrospun template method in which an electrospun water-soluble PVA nanofiber was used as the template. The large volumes of vapors released from the introduced foaming agents are attributed to the production of mesopores with uniform spatial distribution on the whole TiO2 tube wall and these mesopores prevent damage to the TiO2 nanotubular morphology during the PVA template removal. The present work represents a critically important solution in advancing the electrospinning technique for generating mesoporous nanotubes in an effective and facile manner.

Effect of melt and solution electrospinning on the formation and structure of poly(vinylidene fluoride) fibres

We investigated the effects of applied voltage and collector rotating speed on the crystal structure and piezoelectricity of poly(vinylidene fluoride) (PVDF) fibres obtained by two electrospinning (ES) systems; laser-melt electrospinning (M-ES) and conventional solution electrospinning (S-ES). A higher β phase fraction was observed in the S-ES fibres, although the M-ES fibres showed comparable crystallinity. The piezoelectric constant (d33) for the S-ES fibres was also higher than that of the M-ES fibres. This is the first report clarifying the difference between M-ES and S-ES for the formation of PVDF fibres.

Structural analysis of cellulose acetate and zirconium alkoxide hybrid fibres

We investigated the detailed structures of organic–inorganic hybrid fibres composed of cellulose acetate (CA) and zirconium alkoxides (Zr(OR)4) using attenuated total refraction-Fourier transform infrared spectroscopy (ATR-FTIR), energy-dispersive X-ray spectroscopy (EDS), and X-ray absorption fine structure (XAFS) measurements. The fibres were prepared by an air-gap spinning technique, where the acetone solution of CA was injected into a Zr(OR)4–acetone bath. The Zr contents in the prepared fibres increased with increasing Zr(OR)4 bath concentration, but reached steady-state values at Zr(OR)4 bath concentrations above 10 wt%. In addition, EDS analysis for the cross-section of the fibre showed that Zr distribution in the fibre varied depending on Zr(OR)4 bath concentration and alkoxide type. ATR-FTIR and XAFS analysis showed that Zr contained in a CA fibre was hexacoordinated, with a local structure similar to that of hydrolysed Zr(OR)4. This result indicated that the confinement to the CA fibre had little influence on the local structure of Zr.