Minoru Miyauchi

Conductive Cable Fibers with Insulating Surface Prepared by Coaxial Electrospinning of Multiwalled Nanotubes and Cellulose

Core-sheath multiwalled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds of nanometers to several micrometers were prepared by coaxial electrospinning from a nonvolatile, nonflammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose dissolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to remove the IL completely and dried to form core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity because of a conductive pathway of bundled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt % MWNT loading.

Electrospun polyvinylpyrrolidone fibers with high concentrations of ferromagnetic and superparamagnetic nanoparticles.

Electrospun polymer fibers were prepared containing mixtures of different proportions of ferromagnetic and superparamagnetic nanoparticles. The magnetic properties of these fibers were then explored using a superconducting quantum interference device. Mixed superparamagnetic/ferromagnetic fibers were examined for mesoscale magnetic exchange coupling, which was not observed as theoretically predicted. This study includes some of the highest magnetic nanoparticle loadings (up to 50 wt%) and the highest magnetization values (≈ 25 emu/g) in an electrospun fiber to date and also demonstrates a novel mixed superparamagnetic/ferromagnetic system.

Preparation of synthetic wood composites using ionic liquids

Synthetic wood composite films containing cellulose, hemicelluloses, and lignin, the three major components of natural wood, were prepared in a room temperature ionic liquid solvent, 1-ethyl-3-methylimidazolium acetate, [EMIM][Ac]. Various synthetic wood composites were obtained by dissolution of individual wood components together with additives, including polyethylene glycol (PEG), chitosan, and multi-wall carbon nanotubes (MWNTs) in [EMIM][Ac]. The addition of water affords a gel that was dried in either a low humidity environment or under vacuum. Synthetic wood films showed smoother surface textures, higher water resistance, and higher tensile strengths than cellulose films formed by the same methods. Tailor-made synthetic wood composites were also prepared having a variety of desirable properties, including antimicrobial activities, controlled hydro-phobicity/philicity, high relative dielectric constant, and a high degree of cohesiveness.

Flexible Electrospun Cellulose Fibers as an Affinity Packing Material for the Separation of Bovine Serum Albumin

Flexible, well-dispersed and continuous 100-nm diameter cellulose fibers were prepared from an ionic liquid solvent by a novel dry-jet wet-electro spinning process. The ribbon fibers formed were chemically activated and an affinity dye, cibacron blue (CB) was immobilized at 0.22 g CB/g dry fibers loading to the surface of these fibers. The resulting affinity matrix was packed into a chromatography column and the adsorption, desorption and specificity of this matrix for bovine serum albumin (BSA) was studied. These electrospun fibers had a BSA binding capacity of 230 mg/g, nearly twice that of CB-immobilized 100-?m beads and over ten-fold higher capacity that CB-immobilized cellulose fibers prepared by a conventional electrospinning process. The results of this work suggest that chromatography supports of flexible, well-dispersed, continuous nanofibers may offer advantages over conventional supports in affinity separations.