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Volume 70, Issue 5
Displaying 1-9 of 9 articles from this issue
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Original Papers
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Takuya OHZONO, Kosuke SUZUKI, Tomohiko YAMAGUCHI, Nobuko FUKUDA2013 Volume 70 Issue 5 Pages 179-184
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSRecently, spontaneously formed microwrinkles on hard coating-capped elastomer surfaces have attracted the attention of both the scientific and applied research communities, because of their simple fabrication process and potential for diverse practical applications. The depth and averaged orientation of the microwrinkle grooves can be controlled by applying strain. Here, we study the diffusion of light passed through a surface with wrinkles in the range of hundreds of microns. Without strain, the sample shows no wrinkles and is a transparent plate. With strain, the surface shows wrinkles and diffuses the light beam depending on the magnitude of applied strain. Thus, the present system can be used as a switchable optical diffuser.View full abstractDownload PDF (810K) -
Nami SUGIYAMA, Tatsuo OHNO, Kunibu RYOKO, Mamoru AIZAWA, Yuko TAKEOKA, ...2013 Volume 70 Issue 5 Pages 185-192
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSPoly(L-lactic acid)/hydroxyapatite (PLLA/HAp) composites were fabricated by in situ polymerization of L-lactide in porous HAp disks, using lipase as a catalyst. The effect of using various lipase species on the molecular weight of the resulting PLLA was investigated, as was the effect of varying the lipase concentration. Lipase CA, derived from Candida antarctica, was found to promote the polymerization of L-lactide in bulk form as well as within porous HAp disks. The in situ polymerization of L-lactide within lipase CA-coated HAp disks at 130℃ for 7 days resulted in PLLA/HAp composites with a PLLA content in the range of 16 to 19 wt.%. The weight average molecular weights of the PLLAs formed in these composites were in the range of 1.6 × 104 to 3.0 × 104 g mol−1 and varied with the lipase CA concentration. The PLLA/HAp composites exhibited a maximum bending strength of 72 MPa and a fracture toughness value of 0.93 MPa · m1/2, as estimated by three point bending tests. The cell adhesion and proliferation properties of these materials with osteoblast-like MC3T3-E1 cells suggest that these PLLA/HAp composites have suitably bioactive surfaces.View full abstractDownload PDF (776K) -
Yuji HIRAI, Hiroshi YABU, Masataka KAIDO, Atsushi SUZUKI, Masatsugu SH ...2013 Volume 70 Issue 5 Pages 193-198
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSControl of friction is one of the big issues to resolve energy problems. Unique, superior functional surfaces are formed by self-organization and self-assembly processes in nature. By mimicking such surfaces, we have the possibility to obtain friction-controlling surfaces. We have reported that honeycomb-patterned polymer films and micro lens arrays (MLAs) can be prepared by a self-organization process and simple molding methods. In this study, we prepare silver microdimple-arrays (MDAs) using MLAs as templates and electroless plating of silver and measured surface frictional properties of the resulting silver MDAs. The prepared silver MDAs have hexagonally arranged hemispherical micro pore and spike structures, completely covered with silver. The silver MDAs showed lower friction coefficients than similar flat silver films. These results suggest silver MDAs can be used as low friction surfaces.View full abstractDownload PDF (904K) -
Yusuke NARITA, Wariya SIRITHEP, Yosuke OKAMURA, Yu NAGASE2013 Volume 70 Issue 5 Pages 199-208
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSThe preparation of soluble polyamides, poly(amide-ester) and poly(urethane-urea) containing phosphorylcholine (PC) group was carried out by the polycondensation and polyaddition using an aromatic diamine monomer containing a phospholipid polar group. In the syntheses of poly(amide-ester) and poly(urethane-urea), polycarbonatediol was used as a comonomer to insert a soft segment. The self-standing elastic polymer films could be fabricated from the obtained PC-containing copolymers by the solvent-casting method. In particular, polymer films fabricated from poly(urethane-urea) exhibited the elastic properties similar to commercially available poly(carbonate-urethane), bionate®. It was found that the PC-containing polymer films sufficiently reduced the adhesion of proteins and platelets. Therefore, it was shown that the obtained polymers possess both, high biocompatibility derived from PC group and the elastic properties derived from the main chain structure.View full abstractDownload PDF (1079K) -
Daisuke ISHII, Akihito TAKAHASHI, Masatsugu SHIMOMURA2013 Volume 70 Issue 5 Pages 209-213
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSIn nature, many functional superhydrophobic surfaces have been observed, e.g. on lotus leaves, rose petals and morpho butterflies. We focused on the function of rose petals with nano-micro structured surfaces, showing not only strong water repellency but also size-selective adhesion of water microdroplets. Our group has reported that superhydrophobic surfaces composed of polymer pillar arrays are obtained by peeling off the top layer of self-organized honeycomb-patterned porous films. Furthermore, high adhesive superhydrophobic hydrophilic-dome and hydrophobic-pillar hybrid structures are obtained by deposition of hydrophilic domains into several pores of the honeycomb film before the peeling process. In this report, we describe the fabrication of a superhydrophobic structured surface showing pH-responsive water microdroplet adhesion prepared from a polystyrene honeycomb film. Adhesion of water microdroplets on the surface is controlled by the pH of the water droplets; pinning is found at low pH and rolling at high pH. This surface is expected to facilitate novel applications in microfluidic devices in order to manipulate water droplets under various environments by facile external stimuli.View full abstractDownload PDF (781K) -
Naoki TAKAHARA, Tao WANG, Seung-Woo LEE2013 Volume 70 Issue 5 Pages 214-220
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSA novel combination of cyclodextrin hosts and imprinting effects in TiO2 gel ultrathin layers prepared by the gas-phase surface sol-gel process was demonstrated. For bisphenol A (BPA) imprinting in TiO2 films, a complex of β-CD/BPA (from 1:1 to 3:1) and Ti(O-nBu)4 were alternately deposited on a quartz crystal microbalance (QCM) electrode, and then the BPA template was removed by washing with ethanol. The film formation and sensing ability of the TiO2/(β-CD/BPA) films were confirmed by QCM frequency measurements. The imprinted TiO2/(β-CD/BPA, 2:1) film showed about 7 times higher selectivity than the non-imprinted TiO2/β-CD film, showing a sensitivity lower than 50 ppb to BPA. The present approach has potential for the detection of a variety of organic compounds in liquids and gases.View full abstractDownload PDF (1112K) -
Takahiko HARIYAMA, Masatsugu SHIMOMURA, Yumi YAMAHAMA, Yasuharu TAKAKU ...2013 Volume 70 Issue 5 Pages 221-226
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSUltraviolet light is an important component of the sun lit environment, and is used by a wide variety of animals and plants. We have investigated the detailed correlation between the optical signature of Ranunculus japonicus and its petal structure. Ultraviolet reflection was observed at the front side of the petal except the nectar guide area. Ultra-structural observations revealed the existence of three main layers at the front side: single layered cells containing carotenoid pigments, pyramidal vascular zone and starch layer. However, the region which showed no ultraviolet reflection such as the nectar guide area and the back side of the petal possessed no starch layer. We measured the spectral reflectance of the starch itself, and revealed that the starch reflects the UV light. When we added the ethanol extracted solution of petals to the surface of starch, the spectral reflection curve faithfully resembled the in vivo reflection curve of the front side of Ranunculus.View full abstractDownload PDF (1103K) -
Hiroshi FUDOUZI, Takahiko HARIYAMA, Yumi YAMAHAMA, Shinya YOSHIOKA, Da ...2013 Volume 70 Issue 5 Pages 227-231
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSHierarchical microstructures in beetle epidermis layers enable a wide variety of structural colors. However, conventional artificial mimicking techniques are limited, mainly, to multi-layer film formation or 3D colloidal crystal array assemblies on flat substrates. In this paper, we propose a new method applying hot embossing using a metal mesh pressed onto the self-assembled opal film on a plastic substrate. Firstly, opal films composed of 0.2 µm polystyrene colloids and infilling elastic silicone polymer were coated on flat polyvinyl chloride (PVC) sheets. Then the surface of the opal film was thermally deformed by pressing a micro structured mold into it above the glass transition temperature. Micro- spectroscopic analysis revealed that the spectral reflection from the tip of a convex shaped dome was the same as the one from the flat area under a tilting angle of 25 degrees. Our new method is expected to contribute to the fabrication of future complex biomimetic structural color elements.View full abstractDownload PDF (814K)
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Chihiro URATA, Benjamin MASHEDER, Dalton F. CHENG, Atsushi HOZUMI2013 Volume 70 Issue 5 Pages 232-234
Published: May 25, 2013
Released on J-STAGE: May 24, 2013
JOURNAL FREE ACCESSHard and transparent zirconia films were successfully formed on a polycarbonate (PC) surface under mild preparation conditions (low temperature and ambient-pressure). Our process is based on the lamination of porous anodized zirconia membranes (PAZM) to the PC surface, followed by mechanical peeling with tweezers. By heating PC above its glass transition temperature, molten PC was successfully pulled into the nanopores through capillary force, followed by cooling to readily anchor the PAZM securely to the PC surface. Consequently, our resulting PAZM-laminated PC surface exhibited excellent adhesion and surface mechanical properties, while preserving the optical and bulk properties of the polymer.View full abstractDownload PDF (514K)
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