Nanocelluloses are prepared by downsizing plant cellulose fibers, which are efficiently produced at the industrial level as paper and dissolving pulps from renewable wood biomass resources. The number of scientific publications and patents concerning nanocelluloses has been increasing every year, because nanocelluloses are expected to contribute to creation of a sustainable society partly in place of petroleumbased materials. Nanocelluloses are categorized as cellulose nanonetworks (CNNeWs), cellulose nanofibrils or nanofibers (CNFs), and cellulose nanocrystals (CNCs) depending on their morphologies, originating from crystalline cellulose microfibrils abundantly present in each plant cellulose fiber. When no chemical pretreatment is applied to plant cellulose fibers, only CNNeW-type nanocelluloses with heterogeneous morphologies are obtained even after harsh mechanical disintegration in water. In contrast, when positionselective chemical pretreatment is applied to plant cellulose fibers for introduction of a large amount of charged groups on the cellulose microfibril surfaces, CNFs and CNCs with homogeneous ~3 nm widths can be prepared from the chemically pretreated plant cellulose fibers by gentle mechanical disintegration in water. These charged groups are used as scaffolds to add diverse functionalities to nanocelluloses by simple ion exchange in water. Chemical modifications of nanocellulose surfaces, hydrogels, preparation of nanocellulosecontaining composites with various organic and inorganic compounds, the fabrication processes from nanocellulose/water dispersions to dried films, fibers, and porous materials, as well as their versatile applications, have been extensively reported in the last few years. In this review, some research topics are selected from nanocellulose-related publications and briefly overviewed.

The separation of protein plays a critical role in the protein production process. A functionalized nanofiber fabric was prepared by immobilizing Cibacron Blue (CB) on a polyvinyl alcohol (PVA) nanofiber fabric produced by an electrospinning method. To evaluate its separation performance, the adsorption test of bovine serum albumin (BSA), a kind of protein, was conducted using this fabric. The CB molecules were immobilized by the covalent bonding of hydroxyl group of PVA and chlorinated triazine ring of CB under alkaline condition. The adsorption test of CB-enhanced affinity PVA nanofiber fabric was conducted by soaking it into the BSA solution as an adsorbate. As a result, after enhancing affinity by CB, the BSA adsorption amount of the PVA nanofiber fabric indicates a significant increase due to functionalization. Moreover, the adsorption characteristics were heavily dependent on the solution environment.

Poly[N-(2-Hydroxypropyl)methacrylamide] (PHPMA) shows excellent biocompatibility and thus is expected to be used as a carrier in a drug delivery system. In this study, we investigated how the difference in the monomer structure influences the sequence in copolymers composed of HPMA and monomers (MA-ahNHNH-Boc and MA-NHNH-Boc); the size of MA-ah-NHNH-Boc is larger than that of MA-NHNH-Boc by the alkyl chain (CH2)5 spacer. Because the obtained copolymers showed a phase separation behavior upon heating,we also investigated this phase separation behavior by turbidimetry and the molecular dimension in dilute aqueous solution by small-angle X-ray scattering (SAXS). Consequently, we found that the difference between the monomers (MA-ah-NHNH-Boc or MA-NHNH-Boc) significantly influences the monomer sequence in copolymer chains, the cloud point temperature, and the chain dimension in aqueous solution.

This study investigated the effects imparted to paper handsheets by the addition of reed cellulose nanofibrils (RCNF) and ultrasonic treatment of the handsheets. RCNF addition, especially when combined with ultrasonic treatment, increased the density and tensile strength of the handsheets. The tensile strength increased from 38.9 to 62.6 N・m/g, when 5 wt% RCNF were added and ultrasonic treatment was performed for 20 min. Basically, the increase in tensile strength was due to an increase in the inter-fiber bonding strength, which conformed to the Page equation. The addition of RCNF decreased the number of voids at the handsheet surface and increased the inter-fiber bonding, as confirmed by scanning electron microscopy images. The number of such voids was further reduced and inter-fiber bonding was increased by the ultrasonic treatment.

The effects of melt-spinning speed (400–1200 m/min) on fiber structure development after necking were analyzed by wide-angle X-ray diffraction (WAXD) / small-angle X-ray scattering (SAXS) images taken with the time resolution of 0.19–0.34 ms during continuous drawing under the same drawing stress. Whereas an a*-axis oriented crystal and a low-oriented long-period structure was formed at lower speeds, a c-axis oriented crystal and highly oriented long-period structure were formed at higher speed. The long-period structure and low-oriented crystal survived for several hundred microseconds after necking, and after the breakdown of that structure, a highly c-axis oriented long-period structure and mesophase were reconstructed. A longer time was required for the structural change in the fibers spun at lower speed, likely because of stress bearing of the surviving a*-axis oriented crystals.

Uninterrupted vital-sign monitoring is one of the application field of the so-called “smart textiles”from the increasing demand for health care demands. Most of the so-called smart textiles have been employed conductive fibers for sensing and signal transformation, but very few employed fiber Bragg grating (FBG) sensor, which can be used as “multi vital sign sensor”. Although the demands for blood glucose monitoring is increasing, no smart textile has been investigated from the viewpoint. We demonstrated at the first time in this paper that FBG sensor could sense blood glucose level and could be expected manner in the textile form. We installed the FBG sensor on the subjectʼs wrist and measured pulse wave. The subject had a meal as a glucose load during the measurement. As pulse wave pattern data from FBG sensor system includes information about several other vital signs, we isolated blood glucose information by using hierarchical neural network analysis. The isolated data provided a calibration curve with an extremely high correlation coefficient to the blood glucose. The calculated values are evaluated by dedicated indicator, and we found there are only small error which we can ignore clinically. Comparing with the former studies, we efficiently achieved feature extraction, and the stability of measurement was improved. Although the result represents the first successful method for realizing more accurate non-invasive blood glucose measurement systems aim to smart textile, this result is good enough even at this stage, and we are expecting for practical use in near future. The successful results lead the development of smart textiles for the uninterrupted non-invasive measurement.

In this review, I describe stimuli-responsive colloidal assemblies prepared from a rigid rod-like clay mineral called imogolite, and relate them to their structural characteristics. When combined with dicarboxylic acids, imogolite formed gels that exhibited keen thixotropy, and physical anisotropy via orientation of the imogolite particles after flowing and subsequent standing. Robust hydrogels were also obtained by in-situ polymerization of vinyl monomers in imogolite aqueous dispersion. Under strain, these hydrogels showed a reversible isotropic–anisotropic structural transition.

With the aim of producing polylactide fibers consisting of highly oriented stereo-complex (SC) crystals, high-speed bicomponent melt spinning of the islands-in-the-sea (I/S) fibers consisting of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) as the sea and island components, respectively, was performed. For comparison, bicomponent spinning of the core-sheath (C/S) fibers consisting of PLLA and PDLA as the sheath and core components was also carried out. Structure analysis of the C/S fibers revealed that the orientationinduced crystallization of the higher molecular weight component, PLLA, started from the take-up velocity of around 4 or 5 km/min, whereas there was a significant orientation relaxation of the lower molecular weight component, PDLA, with the further increase of take-up velocity up to 10 km/min. After the on-set of orientation-induced crystallization, development of only homo-crystals was confirmed through the wide-angle X-ray scattering analysis. On the other hand, through the differential scanning calorimetry (DSC) of the I/S fibers, along with the melting peak of homo-crystals, distinct melting peak of the SC crystals was observed. This result suggested the mutual diffusion of PLLA and PDLA molecules during the DSC analysis. Based on these results, post-annealing of the as-spun fibers was attempted at the temperatures of 120 and 190 ̊C,considering the melting temperatures of the homo and SC crystals of 160 and 220 ̊C. It was found that the high -speed spun I/S fibers could maintain their shapes after the annealing at 190 ̊C under constant length condition if the orientation-induced crystallization proceeded in the spinning process. After the annealing,fibers consisting of a large amount of highly oriented SC crystals was formed successfully, indicating that the diameter of the island fibers was small enough for the efficient mutual diffusion of the PLLA and PDLA molecules in the fiber cross-section.

Cerium oxide (CeO2, ceria) particles were supported on cotton and nylon fabrics by immersing the fabrics into the solution containing cerium chloride (CeCl3) with bubbling of ozone (O3) gas. The amount of supported ceria on the fabrics was increased with increasing of [CeCl3] concentration and immersing period. Ultraviolet-visual (UV-vis) spectra of the fabrics revealed that ultraviolet (UV) shielding properties were enhanced by the supporting of the particles and the properties were kept after washing with water and SDS solution. The exposure to UV light reduced stretching strength and breaking extension of the nylon fabric supported by titanium oxide (TiO2, titania) particles, but they never reduced those of the fabrics supported by ceria particles.

We have developed a device for the simultaneous measurements of viscosity and light transmittance. In general, aqueous solutions of associative polymers often show gelation and/or phase separation. Viscometry and light transmittance have been standard methods in order to evaluate the gelation and phase separation,respectively. However, so far, a unified device to evaluate the both phenomena simultaneously has not been available, although such a device should bring numerous benefits to understanding the mechanism of the gelation and phase separation of aqueous associative polymers. In this study, constitution of the device and several examples of the device are presented.