Koji Kuraoka

Preparation of a membrane with aligned nanopores using an organic–inorganic hybrid technique

High performance membranes having aligned nanopores were prepared by an organic–inorganic hybrid process using an electric field to align the liquid crystal molecules therein.

Properties of modified surface for biosensing interface

Properties of modified surface, behavior against salting-out effect, suppressive effect for protein nonspecific adsorption, and wettability were examined using various mercapto compounds bearing methyloligoethylene glycol, oligoethylene glycol, alkyl oligoethylene glycol, alkyl phosphoryl choline, alkyl inverse phosphoryl choline, and alkyl sulfobetaine moieties. The behavior against salting-out effect was examined using gold nanoparticle with PBS and NaCl aqueous solution. The suppressive effect for protein nonspecific adsorption was evaluated by SPR, and the wettability was measured on the SPR chip. The gold nanoparticle modified with 8C3EG, 12C4EG, 12CPC, 6CCP, and 12CCP showed excellent behavior against salting-out effect. The suppression of protein nonspecific adsorption was effective with 6EG, 12C4EG, 12CPC, and 12CS. On the other hand, the modified surface possessed high wettability except for the surface modified with M6EG. The results indicate that incorporation of alkyl group into surface modification materials is effective for the enhancement of behavior against salting-out effect and suppressive effect for protein nonspecific adsorption regardless of wettability. Among the zwitter ionic derivatives, inverse phosphoryl choline derivatives showed intriguing properties, high behavior against salting-out effect with high wettability but low suppressive effect for protein nonspecific adsorption.

Solid electrolyte membranes based on PVPA and alkoxysilane for intermediate-temperature fuel cells

A proton-conducting solid electrolyte membrane based on polyvinyl phosphonic acid (PVPA) and 3-glycidoxypropyltrimethoxysilane was developed via the sol–gel process. The electrical conductivity of the organically modified membrane obtained with optimum composition was 3.7 × 10 −2 S/cm at 80°C under 90% relative humidity (RH), which was sufficient for its practical use as a solid electrolyte for fuel cells. In addition, a membrane based on polyphosphoric acid (PPA) and alkoxysilane was fabricated for comparison, by employing polyethylene glycol dimethacrylate (PDM) as an additive. Although the PPA system (with PDM) exhibited similar electrical conductivity to the PVPA system, the latter had superior mechanical strength and flexibility. Furthermore, the PVPA-based membrane with optimum composition was thermally stable up to ca. 200°C. The membrane exhibited electrical conductivity of 1.3 × 10 −2 S/cm at 125°C even under 30% RH, which was similar to that of Nafion® at the same temperature under 100% RH.