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This study describes the Ku -band 70- and 30-W-class internally matched gallium nitride (GaN) power amplifiers (PAs) for multi-carrier satellite communications (SatComs). The GaN PAs maintain low third-order intermodulation distortion (IMD3) over a wide offset frequency range of up to 400 MHz, whereas in the Ku -band, one PA can deliver a high peak output power of approximately 70 W and the other PA, a peak output power of higher than 30 W. To realize a wide offset frequency operation, our proposed output-matching circuit includes three different types of difference-frequency short circuits, two of which are embedded into a tournament-shaped output-matching circuit inside the PA package and the rest is embedded into the drain bias feed placed outside the package. To verify the short-circuit design and its effectiveness, two different power classes (70 and 30 W), Ku -band GaN PAs, were designed and fabricated, and then, their output transfer characteristics focusing on IMD3 were measured. The measurements show that the 70-W-class GaN PA achieves a peak output power of 48.6 dBm while maintaining a linear output power of over 40 dBm and an IMD3 of less than −26 dBc over wide offset frequencies ranging from 1 to 400 MHz. The 30-W-class GaN PA maintains a linear output power of over 36.3 dBm and an IMD3 of less than −27 dBc over wide offset frequencies of up to approximately 600 MHz. To the best of the authors’ knowledge, these PAs have a record output power level over a wide frequency range of 1–400 MHz or higher under the condition of a low IMD3 of less than −25 dBc, compared to previously reported Ku -band GaN PAs used for multi-carrier SatComs.

In this study, we investigate what types of cellulosic materials are formed by soaking the cellulose/ionic liquid (1-butyl-3-methylimidazolium chloride, BMIMCl) solutions in various organic liquids. When the 5-wt% cellulose/BMIMCl solutions were soaked in organic liquids with high and moderate polarities (relative permittivities), the corresponding cellulosic solutions and gels were produced, respectively. On the other hand, soaking the cellulose/BMIMCl solutions in lower polar liquids resulted in aggregation of cellulose in the mixtures. As the gels with high boiling point media were stable, they were characterized by viscoelastic and compression measurements. Contents of organic media and BMIMCl in the gels were changed depending on the polarities, which affected the mechanical properties under compression mode. Furthermore, processes for production of the solution, gel, and aggregate were proposed.

Herein, we report the fabrication of paperlike chitin sheets (chitin paper) by the extensive entanglement of self-assembled nanochitins formed using a bottom-up approach involving stepwise regenera...

This study investigated Pickering emulsion polymerization of styrene using self-assembled chitin nanofibers (CNFs) as stabilizers to produce CNF-based composite particles, which were further converted into hollow particles. Previously, we reported that regeneration from a chitin/1‑allyl‑3‑methylimidazolium bromide ion gel using methanol fabricated self-assembled CNFs. Prior to the emulsion polymerization, CNFs were maleylated by reaction with maleic anhydride in the presence of perchloric acid. After styrene was added to a dispersion of the produced anionic CNFs in ammonia aq., a mixture was ultorasonicated to give an emulsion, in which styrene droplets were stably surrounded by CNFs. Radical polymerization was then conducted in the presence of potassium persulfate as an initiator to produce the composite particles. Particle sizes became smaller as the amounts of CNFs increased. The hollow particles were prepared by solubilizing out the polystyrene cores with toluene.

In this study, we investigate the Pickering emulsion polymerization of styrene using scaled-down chitin nanofibers (SD-ChNFs) as stabilizers to produce nanochitin/polystyrene composite particles. Prior to emulsion polymerization, an SD-ChNF aqueous dispersion was prepared by disintegrating bundles of the parent ChNFs with an upper hierarchical scale in aqueous acetic acid through ultrasonication. After styrene was added to the resulting dispersions, the mixtures at the desired weight ratios (SD-ChNFs to styrene = 0.1:1–1.4:1) were ultrasonicated to produce Pickering emulsions. Radical polymerization was then conducted in the presence of potassium persulfate as an initiator in the resulting emulsions to fabricate the composite particles. The results show that their average diameters decreased to a minimum of 84 nm as the weight ratios of SD-ChNFs to styrene increased. The IR and 1H-NMR spectra of the composite particle supported the presence of both chitin and polystyrene in the material.

Generally, an optical lens is reduced its reflection by multilayer anti-reflection coating. However, there are some problems, for example, those coatings cannot be attached for some kind of resins, and show clack or peeling by temperature change or humidity. Lately, anti-reflection effect by sub-wavelength structure on optical lens surface is studied widely. This is called ARS, Anti-Reflective Structure. ARS solved above problems, and has low dependence on incident angle of light. Conventionally, for mass production of ARS lens, we tried injection molding. That is, fabricating fine structure on mold core, and transfer the structure to plastic resin. However, the transferring is very difficult, because of its fineness and adhesion resin to the core. Besides, mold for high transcription is expensive. We tried to fabricate ARS on plastic lens surface by Reactive Ion Etching. Controlling plasma condition at each etching process cleverly, we successfully obtained fine ARS on optical lens surface. The structure has high aspect and narrow pitch which is about 0.1μm, and show good anti-reflective property.

Polymer nanohybrid materials that consist of poly(vinyl alcohol) (PVA) and aluminosilicate nanofiber imogolite were prepared by effective dispersion of aluminosilicate nanofiber in a polymer matrix by an in situ synthetic method. The as-synthesized imogolite–PVA hybrid was characterized by infrared spectroscopy, wide angle X-ray diffraction and atomic force microscopic observations. The imogolite–PVA hybrid film was highly transparent compared with imogolite–PVA blend film, which was prepared by a solution blend of the freeze-dried imogolite powder with PVA. In addition, compared with PVA film, the hybrid films showed an increase in the elastic modulus and heat distortion temperature. These results indicate that in situ synthesis of imogolite in PVA solution successfully formed the polymer nanohybrid with finely-dispersed nanofillers.

In this study, chitin was nanofibrillated, cationized, and then used as a reinforcing agent for xanthan gum hydrogels. Amidinated chitin nanofibers (CNFs), which were prepared by partial deacetylation of the nanofibrillated chitin and the subsequent reaction of the generated amino groups with N,N-dimethylacetamide dimethyl acetal, were converted into an amidinium chitin bicarbonate with nanofiber morphology by CO2 gas bubbling and ultrasonic treatments in water. Xanthan gum hydrogels, which were prepared by exchange of disperse media from xantham gum ion gels with 1-butyl-3-methylimidazolium chloride, were then soaked in the resulting cationic CNF aqueous dispersions with different degrees of substitution (DSs) of amidinium groups to progress composition, giving rise to the CNF-reinforced xanthan gum hydrogels. The presence of CNFs in the hydrogels was confirmed by SEM measurement of the lyophilized samples. The amounts of CNFs in the hydrogels increased with increasing the DS values. The compression testing of the hydrogels suggested the reinforcing effect of CNFs, which were induced by electrostatic interaction owing to anionic nature of xanthan gum.

In this study, we investigated the preparation of cationic/anionic chitin nanofiber (CNF) composite materials by electrostatic interaction. An aqueous dispersion of amidinium CNF was prepared by a top-down approach, and a maleylated CNF film was obtained by a bottom-up approach from a chitin ion gel in an ionic liquid with subsequent maleylation on the CNFs. The resulting film was dispersed in ammonia (aq), which was then mixed with the aqueous cationic CNF dispersion to give the composite film. The composition of the two CNFs was evaluated by scanning electron microscopy and X-ray diffraction measurements. Tensile testing results indicated that the mechanical properties of the composites were enhanced with increasing degrees of substitution of the cationic and anionic groups on CNFs, and also when the molar ratio of these groups approached 1:1. The dissociation of the two kinds of CNFs by alkaline treatment of the composite film was achieved, suggesting the presence of an electrostatic interaction among the interactions between them.

This study investigated the fabrication of a nanochitin film via the aggregation of scaled-down chitin nanofibers (SD-ChNFs). A self-assembled ChNF film, which was prepared by regeneration from a chitin/ionic liquid ion gel using methanol, followed by filtration, was treated with aqueous NaOH for deacetylation and subsequently disintegrated by cationization and electrostatic repulsion in 1.0 mol/L aqueous acetic acid with ultrasonication to give a SD-ChNF dispersion. Isolation of the SD-ChNFs via filtration of the dispersion resulted in a highly flexible self-assembled ChNF film that bent and twisted easily. The film exhibited superior mechanical properties compared to the parent self-assembled ChNF film, where the flexibility was further enhanced by the compositing the SD-ChNFs with an anionic polysaccharide, namely ι-carrageenan, via multi-point ionic cross-linking. These enhanced mechanical properties and efficient compositing properties were attributed to the scaling down of the ChNFs.

In this article, we report the synthesis of a hyperbranched supramolecular polymer composed of continuum of amylose-poly( l -lactide) (PLLA) inclusion complexes by phosphorylase-catalyzed enzymatic polymerization using a branched maltoheptaose-PLLA conjugate according vine-twining polymerization manner. The X-ray diffraction and 1H NMR measurements indicated the presence of the inclusion complex structure in the product. The GPC peak of the amylose segment, which was obtained by alkaline hydrolysis of the vine-twining polymerization product, shifted to the lower molecular weight region, compared with that of the product, supporting the structure of the supramolecular polymer. A hydrogel of the supramolecular polymer was obtained through the formation of an ion gel with an ionic liquid. Furthermore, a cryogel with porous morphology was produced by lyophilization of the hydrogel.

In this study, we investigated the fabrication of porous chitins with continuous channel substructure by regeneration from gels with CaBr2·2H2O/methanol solution. After rapidly removing methanol from the gels, the products were immersed in methanol, followed by washing out CaBr2 with water and lyophilization to obtain regenerated chitins with inter-connected continuous pore morphology. Scanning electron microscopic results supported that the materials were consisted of continuous substructures of porous channels. The materials were further characterized by SEM-EDX and XRD measurements. The mechanical property and water absorbability were also evaluated. The plausible mechanism for the formation of the inter-connected pore morphology during the regeneration procedure was discussed.

In this study, we investigated the preparation of chitin nanofiber (CNF)-reinforced cellulose films through stepwise regeneration procedures from the respective ion gels with ionic liquids. Self-assembled CNF dispersions were prepared by regeneration from the chitin ion gel with the ionic liquid, 1-allyl-3-methylimidazolium bromide, using methanol, followed by dilution with adjusted amounts of methanol. Cellulose ion gels with the ionic liquid, 1-butyl-3-methylimidazolium chloride, were then prepared, soaked in the CNF dispersions, and centrifuged to simultaneously occur regeneration of cellulose and compatibilization with the CNFs. Soxhlet extraction with methanol and subsequent drying of the resulting materials gave the CNF/cellulose composite films. The IR and SEM results of the films indicated the presence of CNFs not only on the surfaces of the films but also inside the films. Powder X-ray diffraction patterns showed the amorphous structure of the cellulose in the film. Tensile testing of the films suggested the reinforcing effect of the CNFs on the mechanical properties of the films.

In this study, we prepared mutiformable functional supramolecular gels by vine-twining polymerization using poly(γ-glutamic acid-graft-e-caprolactone) (PGA-g-PCL) as a new guest polymer, with subsequent procedures of lyophilization and exchange of dispersion media. When the phosphorylase-catalyzed enzymatic polymerization of the monomer α-D-glucose 1-phosphate from a maltoheptaose primer was carried out in the presence of PGA-g-PCL according to the vine-twining polymerization method, a supramolecular hydrogel was obtained. The resulting hydrogel, purified by soaking in water, had the self-standing properties. Macroscopic interfacial healing was achieved by the formation of inclusion complexes at the interface between two hydrogel pieces through enzymatic polymerization. Cryogels were obtained by the lyophilization of the hydrogels; XRD analysis of the cryogel indicated the presence of inclusion complexes of amylose with PCL graft chains in intermolecular (PGA-g-PCL)s, which acted as cross-linking points for hydrogelation. Porous morphologies were seen in scanning electron micrographs of the cryogels. Furthermore, ion gels were fabricated by soaking the hydrogels in the ionic liquid of 1-butyl-3-methylimidazolium chloride. The mechanical properties of the cryo- and ion gels were evaluated by compressive and tensile testing, respectively.

We previously reported the preparation of a self-assembled chitin nanofiber (CNF) film via regeneration from an ion gel with an ionic liquid, followed by sonication and filtration. Based on the finding that CNFs were redispersed in a mixture of the film with ammonia aqueous solution (aq.), in this study, CNF-natural rubber (NR) composite sheets were fabricated by mixing redispersed CNF with NR latex stabilized by ammonia, followed by drying under reduced pressure. Tensile testing of the sheets indicated the reinforcing effect of CNFs. Further, CNF-NR composite porous materials were fabricated by evaporating ammonia from the CNF-NR dispersion, followed by lyophilization. The mechanism for the formation of porous structures was evaluated.

This paper reports the preparation of chitin nanofiber-graft-poly(2-hydroxyethyl acrylate) (CNF-g-polyHEA) films by surface-initiated atom transfer radical polymerization (ATRP) of HEA monomer from a CNF macroinitiator film. First, a CNF film was prepared by regeneration from a chitin ion gel with an ionic liquid. Then, acylation of the CNF surface with α-bromoisobutyryl bromide was carried out to obtain the CNF macroinitiator film having the initiating moieties (α-bromoisobutyrate group). The surface-initiated graft polymerization of HEA from the CNF macroinitiator film by ATRP was performed to produce the CNF-g-polyHEA film. The IR, XRD, and SEM measurements of the resulting film indicated the progress of the graft polymerization of HEA on surface of CNFs. The molecular weights of the grafted polyHEAs increased with prolonged polymerization times, which affected the mechanical properties of the films under tensile mode.

Organic photovoltaic is one of the solar cell consists of fullerene derivative which is an n-type semiconductor and the conductive polymer as p-type semiconductor. In my research, silicon quantum dots was introduced to the active layer consisting of fullerene derivative (PCBM) and a conductive polymer (PCPDTBT), to prepare the hybrid photovoltaic. The prepared hybrid solar cell with Si quantum dots achieved better cell performance compared with controlled solar cell without quantum dots. The hybrid solar cell showed larger value of Incident photon-to-current conversion efficiencies and lower photoluminescence intensity. This indicated that domain size among phase separation in active layer was made smaller than the active layer of controlled solar cell, by introducing Si quantum dots. This change of aggregation structure by quantum dots was contributed to the improvement of cell characteristics.

In this study, we have performed the preparation of reswellable amorphous porous celluloses through regeneration from hydrogels. The cellulose hydrogels were first prepared from solutions with an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), in different concentrations. Lyophilization of the hydrogels efficiently produced the regenerated celluloses. The powder X-ray diffraction and scanning electron microscopic measurements of the products suggest an amorphous structure and porous morphology, respectively. Furthermore, the pore sizes of the regenerated celluloses, or in turn, the network sizes of cellulose chains in the hydrogels, were dependent on the concentrations of the initially prepared solutions with BMIMCl, which also affected the tensile mechanical properties. It was suggested that the dissolution states of the cellulose chains in the solutions were different, in accordance with the concentrations, which representatively dominated the pore and network sizes of the above materials. When the porous celluloses were immersed in water, reswelling was observed to regenerate the hydrogels.

This paper reports the preparation of cellulose/xanthan gum composite films and hydrogels through gelation with an ionic liquid. Mixtures of cellulose and xanthan gum in desired weight ratios with an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), were thinly placed on a Petri dish and heated at 100 °C for 9 h to obtain the solutions. Then, the solutions were left standing at room temperature for 1 day for the progress of gelation. The resulting ion gels were subjected to Soxhlet extraction with ethanol to remove BMIMCl, followed by drying under ambient conditions to obtain the composite films. The crystalline structures of the polysaccharides and the mechanical properties were evaluated by powder X-ray diffraction measurement and tensile testing of the films, respectively. The ion gels in various cellulose/xanthan gum weight ratios, which were prepared in a test tube by the same procedure, were immersed in water for the exchange of disperse media to obtain the cellulose/xanthan gum composite hydrogels. Water contents of all the materials were higher than 90 %. The mechanical properties of the hydrogels were evaluated by compressive testing.

In this paper, we report the formation of hierarchically self-assembled nanofiber films from amylose-grafted sodium carboxymethyl celluloses (NaCMCs) that were synthesized by a chemoenzymatic approach. First, maltooligosaccharide primer-grafted NaCMCs were prepared by a chemical reaction using two kinds of NaCMCs with different degrees of polymerization (DPs) from Avicel and cotton sources. Then, phosphorylase-catalyzed enzymatic polymerization of α-d-glucose 1-phosphate from the nonreducing ends of the primer chains on the products was conducted to produce the prescribed amylose-grafted NaCMCs. The films were obtained by drying aqueous alkaline solutions of the amylose-grafted NaCMCs. The scanning electron microscopy (SEM) image of the film fabricated from the material with the higher DP from the cotton source showed a clear, self-assembled, highly condensed tangle of nanofibers. The SEM image of the material with the lower DP from the Avicel source, on the other hand, showed an unclear nanofiber morphology. These results indicate that the DPs of the main chains in the materials strongly affected the hierarchically self-assembled nanofiber formation. The SEM images of the films after washing out the alkali, furthermore, showed that the fibers partially merged with each other at the interfacial area owing to the double helix formation between the amylose-grafted chains. The mechanical properties of the films under tensile mode also depended on the self-assembled morphologies of the amylose-grafted NaCMCs from the different sources.

In the previous study, we successfully prepared a chitin nanofiber film by regeneration from a chitin ion gel with an ionic liquid using methanol. In this study, we performed surface-initiated graft polymerization of γ-benzyl l-glutamate N-carboxyanhydride (BLG-NCA) from amino groups on a partially deacetylated chitin nanofiber (PDA-CNF) film. First, the chitin nanofiber film was immersed in 40 % NaOH aq. at 80 °C for 7 h for partial deacetylation. Then, the PDA-CNF film was immersed in a solution of BLG-NCA in ethyl acetate at 0 °C for 24 h for graft polymerization from amino groups on nanofibers to give a chitin nanofiber-graft-poly(γ-benzyl l-glutamate) (CNF-g-PBLG) film. The analytical results of the film indicated that graft polymerization of BLG-NCA occur on surface of nanofibers. Furthermore, the film was treated with 1.0 mol/L NaOH aq. to convert PBLG on nanofibers into poly(γ-l-glutamic acid sodium salt) (PLGA). Then, condensation of the resulting carboxylates with amino groups at the terminal ends of PLGAs or the remaining amino groups on nanofibers was performed using the condensing agent to produce a CNF-g-PLGA network film. The resulting film showed the good mechanical properties with high flexibility, which has potentials as promising materials for practical applications.

This paper reports the preparation of chitin/cellulose films compatibilized with polymeric ionic liquids. In-situ (co)polymerization of polymerizable ionic liquids, 1-(3-methacryloyloxypropyl)-3-vinylimidazolium bromide (1) and 1-methyl-3-vinylbenzylimidazolium chloride (3), was carried out in the presence of a radical initiator, AIBN, in the chitin/cellulose solution with ionic liquid solvents (1-butyl-3-methylimidazolium acetate and chloride, BMIMOAc and BMIMCl, respectively), followed by the appropriate procedure to give the desired films. The presence of the polymeric ionic liquid in the film was confirmed by the IR measurement. The powder X-ray diffraction analysis suggested that crystalline structures of the polysaccharides were largely disrupted in the film, as same as that of a chitin/cellulose film prepared by the AMIMOAc/BMIMCl system. These results were different from the XRD result of a chitin/cellulose film prepared by the 1-allyl-3-methylimidazolium bromide/BMIMCl system reported in our previous study, in which some crystalline structures were still remained in the film. Furthermore, the mechanical properties of the present films were evaluated by tensile testing, which were affected by the molar ratios of the polymeric ionic liquids to the polysaccharides and the compositional ratios of the two units 1 and 3.

A hole formed in photo-excited dye molecule under illumination is transferred to cathode with iodine ion in electrolyte solution in the dye-sensitized solar cell developed by M. Gratzel and the conductivity of the iodine ion affects conversion efficiency of the cell. In this work, effect of the polymeric p-type semiconductor on the hole transferability is investigated. PEDOT:PSS and P3HT were used as the p-type semiconductors. Dye-sensitized solar cells were composed of aluminium plate, Nb-doped TiO2 layer adsorbed with TCNQ, the electrolyte solution containing iodine ions, and ITO glass plate. In a solid-type cell substituted the electrolyte solution with the p-type semiconductor, photocurrent was not generated. The photocurrent was generated in the solar cell by introducing the electrolyte solution containing iodine ions between the ITO glass and the p-type semiconductor formed on the dye-adsorbed Nb-doped-TiO2 layer or between the dye-adsorbed Nb-doped-TiO2 layer and the p-type semiconductor formed on ...

To improve the light-to-electric energy conversion efficiency of a dye-sensitized solar cell, a p-type semiconductor electrode was introduced to the cell so that n/p tandem-type solar cell was comp...

This paper reports the preparation of chitin nanofiber-graft-poly( l -lactide-co-e-caprolactone) films by surface-initiated ring-opening graft copolymerization of l -lactide (LA)/e-caprolactone (CL) monomers from chitin nanofiber films. First, the chitin nanofiber film was prepared according to our previous method. Then, the film was immersed in water and lyophilized for pre-treatment. The non-treated or pre-treated film was immersed in a solution of LA/CL in toluene for 12 h. After tin(II)-2-ethylhexanoate as a polymerization catalyst was added to the mixture, which was heated at 80 °C for 48 h for the progress of copolymerization, the resulting film was washed and further subjected to Soxhlet extraction with chloroform. The IR spectrum of the obtained film exhibited carbonyl absorption at 1739 cm−1 due to the ester linkage of poly(LA-co-CL), suggesting the presence of poly(LA-co-CL). The powder X-ray diffraction and SEM measurements of the obtained film indicated that the graft copolymerization of LA/CL was initiated from hydroxy groups on surface of the chitin nanofibers. The mechanical properties of the films, which were evaluated by tensile testing, were affected by the amounts and the LA/CL composition ratios of the grafted polyesters.

TiO2 film covered with Cu-contained layer is prepared by plasma CVD using copper(II) acetylacetonate gas and then heat-treated at 723 K in air. A surface layer of plasma CVD-treated TiO2 film is composed of Cu, C, and O atoms and shows visible light absorption. The plasma CVD-treated TiO2 film can decompose isopropanol into acetone and CO2 under visible light irradiation to appear visible light activity. It is assumed that photo-excited electron reduces directly Cu contained in the surface layer and the reduced Cu can reduce O2 with two and four electrons to form H2O2 and H2O, respectively, since it is confirmed from XPS analysis that C-doping does not take place with the plasma CVD and the origin of the visible light activity is not C-doping.

We investigated the effect of grafted polymer architectures of temperature-responsive poly( N -isopropylacrylamide- co -2-carboxyisopropylacrylamide) (P(NIPAAm- co -CIPAAm)) as an ‘on–off’ switchable surface trap for the effective separation of bioactive molecules in a self-heating, temperature-responsive chromatography system. P(NIPAAm- co -CIPAAm)s were covalently grafted onto amino-modified magnetite–silica composites by a “grafting-to” method. Different architectures of grafted polymers on the magnetite–silica composites were successfully prepared by varying the composition of CIPAAm while keeping their grafted polymer densities constant ( i.e. , introducing more CIPAAm content provided more immobilizing points and reduced grafted polymer chain mobility). Heat was generated at the composite surface by exposing the magnetite–silica composites to an alternating magnetic field (AMF). Raising the temperature above the lower critical solution temperature (LCST) of the polymer resulted in a hydrophilic to hydrophobic phase change in the grafted P(NIPAAm- co -CIPAAm) layers. To assess the effect of grafted P(NIPAAm- co -CIPAAm) architectures on their interaction with bioactive compounds above their LCST, P(NIPAAm- co -CIPAAm)-grafted magnetite–silica composites were packed into a glass column of an aqueous liquid chromatography system and the elution profiles for steroids were analyzed as a function of temperature. At the ‘on’ state of the AMF, the retention times for hydrophobic steroids dramatically increased according to the trend: hydrocortisone co -CIPAAm) above the LCST was restricted when the polymer was immobilized via multiple amide bonds. The proposed system could be very useful for separation of bioactive compounds because their elution profiles can be easily controlled only by ‘on–off’ switching of an AMF, thus eliminating the need for toxic organic solvents and heating/cooling processes of the entire mobile phase.

In this study, we performed the facile preparation of chitin/cellulose composite films using two ionic liquids, 1-allyl-3-methylimidazolium bromide (AMIMBr) and 1-butyl-3-methylimidazolium chloride (BMIMCl); the former dissolves chitin and the latter dissolves cellulose. First, solutions of chitin in AMIMBr and cellulose in BMIMCl were individually prepared by heating each mixture at 100 °C for 24 h. Then, the homogeneous mixture of the two solutions was thinly casted on a glass plate, followed by standing at room temperature for 2 h. After the material was subjected to successive Soxhlet extractions with ethanol for 12 h and with water for 12 h, the residue was dried at room temperature to give a composite film. The crystalline structures of the polysaccharides were evaluated by the X-ray diffraction measurement. Furthermore, the thermal stability and mechanical property of the resulting composite film were estimated by the thermal gravimetric analysis measurement and tensile testing, respectively.

Reduction of methylene blue (MB) occurred by photo irradiation at 280 - 370 nm wavelengths to a solution of MB in an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), which was confirmed by color change and UV-Vis measurement of the solution. Furthermore, the reduced MB was oxidized again by standing the solution under the conditions of light shielding at 50?C. The fluorescence spectra of the solution excited at 350 nm suggested that the photo-induced reduction probably took place via electron-transfer from BMIMCl to MB.

Our previous research showed that a simple ultra-high-pressure process made poly(vinyl alcohol) (PVA) solution into a macrogel and nanoparticles. To investigate the release properties of PVA hydrogels prepared by the ultra-high-pressure treatment, we prepared hydrogels containing model drugs by pressurizing a PVA solution with Alfa-G Hesperidin or Oil Blue N as a water-soluble or an oil-soluble model drug, respectively. In the case of the oil-soluble drug, an oil-in-water emulsion, Oil Blue N containing dodecane in a PVA solution, was used by homogenization before pressurization. The average diameter and the diameter distribution of oil droplets before and after the ultra-high-pressure treatment were almost the same. However, the PVA hydrogel prepared at 10,000 atm for 10 min exhibited the slowest release rate of model drugs. Thus, we found that the release rates of the model drugs from the PVA hydrogels were controlled by the degree of crosslinking in the resulting gels, which was determined from the operation parameters of the ultra-high-pressure treatment, such as the pressure, time, and concentration of the PVA solution. Therefore, an ultra-high-pressure process is promising for drug-carrier development because of the nonharmful simple preparation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

This paper presents an overview on recent developments of imogolite reinforced nanocomposites, including fundamental structure, synthesis/purification of imogolite, physicochemical properties of nanocomposites and potential applications in industry. The naturally derived nanotubular material of imogolite represents a distinctive class of nanofiller for industrially significant polymer. The incompatibility between the surface properties of inorganic nanofiller and organic matrix has prompted the need to surface modify the imogolite. Early problems in increasing the binding properties of surface modifier to imogolite have been overcome by using a phosphonic acid group. Different approaches have been used to gain better control over the dispersal of nanofiller and to further improve the physicochemical properties of nanocomposites. Among these, polymer grafting, in situ synthesis of imogolite in polymer matrix, and spin-assembly are some of the promising methods that will be described herein. This imogolite reinforced nanocomposite of enhanced optical and mechanical properties, and with unique biological and electronic properties, is expected to become an important category of hybrid material that shows potential for industrial applications.

We have demonstrated the preparation of hybrid films of aluminosilicate nanofiber (imogolite) and water-soluble poly( p -phenylene) (WS-PPP), which has sulfonate groups. The imogolite/WS-PPP hybrid gel could be prepared by mixing a solution of these two materials and subsequent centrifugation. The aluminol (Al OH) groups on the surface of imogolite would be protonated under acidic conditions to afford Al OH 2 + groups that can interact with sulfonate groups (SO 3 − ) of WS-PPP. Based on this ionic interaction, a layer-by-layer (LBL) assembly was applied to fabricate the hybrid films of imogolite nanofibers and WS-PPP. The deposited amounts of WS-PPP and imogolite were measured by quartz crystal microbalance (QCM) measurements and scanning electron microscopy (SEM) observation. Atomic force microscopy (AFM) observation revealed that imogolite nanofibers were well networked in the LBL hybrid film.

In this study, we prepared cross-linked aliphatic polyester derived from branched poly(ɛ-caprolactone (abbreviated as CL)- co - d , l -lactide (abbreviated as LA)) macromonomers with different CL and LA compositions and investigated the effect of thermal properties on their degradation. According to the degradation study, the weight loss became larger with increasing LA composition in poly(CL- co -LA). The introduction of LA units that can degrade easily disturbed the crystallinity of the PCL segments; as result, the hydrolysis became accelerated. Also, we studied the temperature dependency of degradation of a series of cross-linked poly(CL- co -LA) materials with different melting points. We found that the degradation of these materials related closely to the crystallinity, which could be controlled by the composition of CL and LA.

Effective surface modification of poly(N-isopropylacrylamide)-based temperature-responsive polymers onto the magnetite nanoparticles was investigated. To achieve this purpose, layer-by-layer method was applied. This technique is based on sequential chemical reactions between the temperature-responsive polymers with carboxyl groups and other another polymers with amino groups. After the polyion complex formation, carbodiimide chemistry was used to cross-link both the functional polymers. As a result, we could confirm the successful preparation using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and the dispersion measurement of the modified magnetite nanoparticles. The thickness was tunable be the number of the layer-by layer reaction. As expected, the magnetite nanoparticles show the very sensitive temperature-responsive behavior.

In this thesis, we studied the convenient synthesis and characterizations of thermo-responsive materials with double response. To achieve these, AB-type diblock copolymers comprising of poly(N-isopropylacrylamide) (NIPAAm) segment and poly(NIPAAm-co-(N-(hydroxymethyl)acrylamide) (HMAAm)) one were designed. That was synthesized in one-pot using an atom transfer radical polymerization (ATRP) technique. Poly(NIPAAm-co-HMAAm)s synthesized separately showed sensitive thermo-response and the cloud point was completely tunable by the composition of HMAAm. As expected, the block copolymers exhibited double thermo-responsive profiles in aqueous solution. The responsive behavior was discussed by precise trace by 1H NMR and turbidity measurements. From these results, we could confirm almost independent dehydration of each segment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6142–6150, 2008

Preparation, Characterization and Biocompatibility Study of the Scaffold Prototype Derived from Cross-Linked Poly[(e-caprolactone)- co -lactide] for Tissue Engineering Materials

We have proposed a vertical comb-drive MEMS mirror which can be applied for a spectrometer with a phase-shifting method, and fabricated the mirror device using the micro fabrication technology. The configuration of the MEMS mirror was designed with three vertical electrostatic comb-drive actuators and hinges at the periphery of the mirror. In the proposed spectrometer, the phase of the light which is reflected at the movable mirror is changed, and the interferogram is obtained by the movable mirror which is driven precisely. We evaluated the moving characteristics of the fabricated MEMS mirror and confirmed that the MEMS mirror could be driven vertically to about 23μm and also could be tilted. Using this MEMS mirror, we configured the spectrometer with a source of monochromatic light (λ= 405 nm), and evaluated the spectroscopic characteristic in principle. Then, we have confirmed that the fabricated MEMS mirror can be applied to the spectrometer with the phase-shifting method.

A two dimensional sinusoid diffraction grating is developed for a moire-reducing low-pass filter. Typical display units have image pixels arranged systematically in two dimensions, with non-illuminating regions between the image pixels. Using a conventional lens to view this display, the image pixels and the region between the pixels are both magnified, and the resulting image is unpleasant to the human eye, especially with color displays, called the screen door effect. This pixel problem is typically solved with a low-pass filter using a diffraction grating. However, depending on the period of the diffraction grating compared to the period of the image pixels, moire can be seen. In recent years, organic electroluminescence displays with a small fill factor are growing popular, but such displays are usually more prone to the screen door effect and moire. With conventional optical low-pass filters, only the pixel pitch in the vertical and horizontal directions are taken into account, but this is insufficient with small fill-factor pixels, and consideration for various diagonal periods is needed. A two dimensional sinusoid structure diffraction grating is developed for a moire-reducing low-pass filter. The angle of the grating with the image pixel arrangement, the distance between the display and the grating, the grating depth, and the grating period are all chosen appropriately, and take into account multiple non-adjacent diagonal image pixel periods for all colors, consequently reducing moire and the screen door effect. We present the calculations and evaluation results from plastic samples made by lithography tooled molds.