Poly(p-phenylene benzobisthiazole) (PBZT) was crystallized from dilute solution in the presence of single-wall carbon nanotube (SWNT) or multi-wall carbon nanotube (MWNT). In this crystallization condition,SWNT existed as pristine bundles. SWNT bundles and MWNT acted as nucleating agents of PBZT crystallization. The nucleating effect of the SWNT bundle was larger than that of MWNT. Transmission electron microscope observation revealed that the morphology of the PBZT crystal on the carbon nanotube (CNT) could be controlled by crystallization condition such as molecular length of PBZT, H2SO4 concentration,variety of CNT. Thermal stability of PBZT crystallized on the SWNT bundles was discussed by the observation of crystal dissolution temperature.
Polyester fabrics (poly(ethylene terephthalate) (PET) and Ecoface®) were treated with a recombinant cutinase, Cut 190*, from a thermophilic actinomycete (Saccharomonospora viridis AHK 190) for a bio-hydrophilization of polyester fabric surface. After incubation of amorphous PET film with Cut 190* at 50 ̊C,contact angles of water and formamide on the enzyme treated film decreased and polar component of surface free energy, γsd, increased to show the enzyme-hydrophilization of PET surface, indicating the increase of hydrophilic groups (COOH and OH) on the film surface. Similarly, polyester fabrics were treated by Cut 190* at 65 ̊C, and their surfaces were characterized using scanning electron microscopy (SEM), Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) analyses. Enzyme-treated polyester fabrics did not display significant changes by SEM and ATR-FTIR analyses. However, XPS analysis showed that the enzyme-treatment induced significant changes in the region of 3-5 nm depth from the surface. Only enzyme-treated polyester fabrics showed capillary rise of water, which was explained in terms of the increase in surface hydrophilicity. Increased color density of the enzyme-treated fabrics with methylene blue also suggested the increment of COOH groups on the fabric surface. On the other hand, the enzyme treatment did not affect tensile properties, supporting that the enzymatic hydrolysis is limited to the surface of fabrics.
Fiber structure development of the continuous neck-drawing process of Nylon 6 (poly ε-caprolactam) fibers was investigated by in situ wide-angle X-ray diffraction and small-angle X-ray scattering measurements using the ultrahigh luminance synchrotron radiation of SPring-8. Feed speeds of 4 and 25 m/min were used with time resolutions of 1.7 and 0.43 ms, respectively. The estimated temperature of the running fiber jumped from 90 to 140150 ̊C with necking, and reached a maximum temperature of about 185 ̊C. The pseudohexagonal phase was oriented along the fiber axis by necking, and transformed to the α'-crystal from 20 to 110 ms after necking. The ά-crystal transformed to the α-crystal below 130 ̊C. The low-oriented long-period structure of the as-spun fiber disappeared by necking, and a higher oriented long-period structure was reconstructed within 10 ms after necking. The 7.8 nm long-period of the as-spun fiber increased to 9.5 nm with the reconstruction.
A sensitive and selective amperometric glucose biosensor based on a PVA/PAA nanofiber layer deposited on a copper/Ni electrode was investigated. Typically, many currently available point-of-care glucose sensors demonstrate a decreasing response to the analyte in the presence of increasing hematocrit levels (blood-to-plasma difference). A sensor electrode for glucose is described that displays a reduced sensitivity to changes in hematocrit levels. The base layer of the sensor consists of PVA/PAA-GOD-coated nanofibers impregnated with a mixture of glucose oxidase and a ruthenium redox mediator. It has an average diameter of approximately 510 ± 50 nm (100–150 ± 20 nm for the glucose oxidase aggregates), an average pore diameter of 2.7 ± 0.5 μm and a thickness of less than 20 μm. The copper/Ni electrode has a low electrical resistance, less than 0.01 Ω, and it may be possible to mass produce the biosensor electrode with a uniform electrical resistance. The current of the PVA/PAA-GOD-coated nanofiber glucose biosensor shows no hematocrit effect on glucose measurements at hematocrit levels from 35% to 60% for glucose concentrations from 37.1 mg/dL (2.06 mmol/L) to 544.7 mg/dL (30.24 mmol/L). The glucose sensor with a PVA/PAA-GOD-coated nanofiber deposited on a Copper/Ni electrode on PET film exhibits a relatively short response time (approximately 3 s) and a sensitivity of 0.85 μAmM1 with a linear range from 0 to 33 mM glucose. The sensor has excellent reproducibility with a correlation coefficient of 0.9989 and a total nonlinearity error of 2.65%.