Hiroshi Kakehi

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer/anatase titanium oxide nanocomposites possessing photocatalytic activity even after calcination at 1000°C.

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [R(F)-(VM)(n)-R(F)] underwent the sol-gel reaction under alkaline conditions in the presence of anatase titanium oxide nanoparticles (an-TiO(2)) in tetrahydrofuran to give the corresponding fluorinated oligomer/anatase titanium oxide nanocomposites [R(F)-(VM-SiO(2))(n)-R(F)/an-TiO(2)]. Crystalline structure of an-TiO(2) in the nanocomposites thus obtained was found to keep completely its structure without phase transformation to rutile even after calcination at 1000°C, although crystalline structure of the original an-TiO(2) nanoparticles underwent a complete phase transformation to the rutile under similar conditions. Interestingly, R(F)-(VM-SiO(2))(n)-R(F)/an-TiO(2) nanocomposites before and after calcination at 1000°C exhibited the similar photocatalytic activity for the decolorization of methylene blue under UV light irradiation.

Preparation and Properties of Novel Fluoroalkyl End-capped Oligomers/Hydrogarnet Nanocomposites

Novel fluoroalkyl end-capped oligomers/hydrogarnet (katoite) nanocomposites were prepared by the hydrothermal reactions of a stoichiometric mixture of Ca(OH)2, Al(OH)3, and Al2Si2O 5(OH)4 in the presence of the corresponding fluorinated acrylic acid, acryloylmorpholine, and N,N-dimethylacrylamide oligomers. These fluorinated katoite nanocomposites thus obtained are nanometer size-controlled, and were found to exhibit a good dispersibility in water, methanol, ethanol, and tetrahydrofuran. Fluoroalkyl end-capped oligomers were also applied to the dispersion of parent katoite into these solvents; however, a poor dispersiblity for these solvents was observed. On the other hand, fluoroalkyl end-capped 2-methacryloyloxyethanesulfonic acid oligomer [RF—(MES) n—RF] was able to solubilize katoite into water to afford the transparent colorless solution. The obtained RF—(MES) n—RF/katoite nanocomposites were found to exhibit a good antibacterial activity against Staphylococcus aureus, and were also applied to the surface modification of poly(vinyl alcohol) to exhibit a good oleophobicity imparted by fluorine on the surface.