Papers by Atsushi Takahara
Surface functionalization tailors the interfacial properties without impacts on the mechanical st... more Surface functionalization tailors the interfacial properties without impacts on the mechanical strength, which is beneficial for industry and daily applications of various metallic materials. Herein, a two-step surface functionalization strategy, (1) catechol-mediated immobilization of clickable agent and (2) postfunctionalization based on thiol−ene click reaction, is achieved using a copolymer, namely poly[2-(methacryloyloxy)ethylundec-10-enoate]-co-(N-(3,4-dihydroxyphenethyl) methacrylamide) [P-(MEUE-co-DPMAm)]. To reduce the potential side reactions of allylic double bonds in allyl methacrylate during the polymerization, the MEUE are designed and synthesized with better control over the polymer chain growth. The surface functionalization via the two-step method is demonstrated using various thiols, e.g., hydrophobic, hydrophilic, and polymeric thiols under room conditions. Additionally, the hydrophobic-thiol-functionalized anodic aluminum oxide is found to be a candidate for the oil/water separation with a separation efficiency of ∼99.2%. This surface modifier provides practical insights into the further design of functional materials.
Hyomen Kagaku, 2000
Surface structure and surface mechanical properties of organosilane monolayers prepared by the La... more Surface structure and surface mechanical properties of organosilane monolayers prepared by the Langmuir-Blodgett (LB) and chemisorption methods were investigated. The organosilane monolayers with longer alkyl and fluoroalkyl chains were in crystalline state at 293 K. The lateral force of the organosilane monolayers increased with an increase in their chain length. The magnitude of lateral force of the fluoroalkylsilane monolayer was higher than that of the alkylsilane one. This can be attributed to the rigid characteristics of fluoroalkyl chain. The lateral force of the noctadecyltrichlorosilane (OTS) monolayer prepared by the LB method was higher than that of the chemisorbed one because of the higher packing density of alkyl chain for the LB monolayer. Molecular aggregation state of the LB OTS monolayer changed from the rectangular phase to the amorphous one via the hexagonal phase with an increase of temperature. The distinct lateral force decrease for the OTS monolayer was observed at the corresponding temperature range.
Nihon Reoroji Gakkaishi(Journal of the Society of Rheology, Japan), 1995
Hyomen Kagaku, 2003
We here introduce how surface dynamics in polymer films can be examined by lateral force microsco... more We here introduce how surface dynamics in polymer films can be examined by lateral force microscopy. Since the manifestation of lateral force is strongly related to energy dissipation during a tip sliding, lateral force can be regarded as an index of dynamic loss modulus at the surface. As a sample, monodisperse polystyrene (PS) films were used. On the basis of the temperature dependence of lateral force, glass transition temperature at the surface was determined. In addition, by measuring scanning rate vs. lateral force curves at various temperatures, activation energy of the surface segmental motion corresponding to glass transition could be successfully obtained via time-temperature superposition principle. The results of these experiments made it clear that thermal molecular motion at the surface was much more vigorous than that in the interior bulk region. Finally, it is also described that LFM was applied to surface segregation phenomenon in polydisperse PS films.
The Proceedings of the Thermal Engineering Conference, 2004
The Proceedings of the Thermal Engineering Conference, 2004
NIPPON GOMU KYOKAISHI, 2009
Biodegradable segmented poly(urethane)s (SPUs) and poly(urethane-urea)s (SPUUs) were synthesized ... more Biodegradable segmented poly(urethane)s (SPUs) and poly(urethane-urea)s (SPUUs) were synthesized by a standard two-step prepolymer method using two kinds of diisocyanates (methyl 2,6-diisocyanatohexanoate (LDI) and 1,4-diisocyanatobutane (BDI)) and polycaprolactone diol (PCL) as a soft segment combined with two kinds of chain extenders (1,3-propanediol (PDO) and 1,4-butanediamine (BDA)) as a hard segment. Thermal analysis by differential scanning calorimetry, wide angle X-ray diffraction (WAXD), and small angle X-ray scattering measurements revealed that different kinds of diisocyanates and chain extenders in SPUU affected the crystallinity of PCL segment and the microphase separation structure consisted of soft and hard segments. Diffraction pattern in WAXD due to the crystallization of PCL components inhibited in the cases of two SPUUs with LDI-BDA and BDI-BDA hard segments. Furthermore, these two kinds of SPUU showed good elastic properties because the crystallization of PCL component was inhibited by the strong aggregation of hard segments. The mechanical properties and degradability of poly(L-lactide) (PLLA)/SPUU blends were also investigated. A toughness of PLLA was enhanced by blending with SPUU. Also, this blend shows degradation owing to the hydrolysis. It was revealed that brittleness of PLLA was improved through blending with biodegradable SPUU without sacrificing degradability.
Nihon Reoroji Gakkaishi, 2002
Fatigue behavior of HDPE extrudates was investigated on the basis of nonlinear dynamic viscoelast... more Fatigue behavior of HDPE extrudates was investigated on the basis of nonlinear dynamic viscoelastic analyses. The HDPE extrudate was prepared by a solid-state extrusion at an extrusion temperature of 353 K with an extrusion ratio of 11.1. Fatigue tests were carried out under the conditions of strain-controlled frequency of 11 Hz and environmental temperature of 303 K. Three deformation conditions were applied to fatigue tests: tension-tension, tension-compression and compression-compression deformation. Relationship between stress and strain amplitudes during fatigue process indicated that in the cases of tension-compression and compression-compression deformations, fatigue lifetime remarkably decreased with increasing dynamic strain amplitude. Nonlinear viscoelasticity during fatigue process was evaluated quantitatively by nonlinear viscoelastic parameter NVP. With increasing imposed strain amplitude, nonlinear viscoelasticity under compression-compression deformation became more remarkable because kink-bands were formed and stress distribution became inhomogeneous. Analyses of hysteresis loss during fatigue process indicated that nonlinear viscoelasticity was closely related to hysteresis loss consumed for irreversible structural change. In particular, in the case of compression-compression deformation, nonlinearity of viscoelasticity increased remarkably with hysteresis loss consumed for structural change due to kink-band formation.
Hyomen Kagaku, 2006
We have proposed herein a novel microfabrication method for polymer ultrathin films that utilizes... more We have proposed herein a novel microfabrication method for polymer ultrathin films that utilizes fluoroalkylsilane monolayer patterned substrates and ink-jet technology. The purpose of this study is to establish the fundamental methods for site-selective formation of polymer thin film utilizing wetting contrast of patterned fluoroalkylsilane monolayer (Rf)／silanol (Si-OH) surfaces. Rf／Si-OH patterned surface prepared by the VUV-rays lithography have lyophobic Rf and lyophilic Si-OH phases, respectively. Polystyrene/xylene solution was used to coat the patterned surface with wetting contrast by the ink-jet method. The patterned polystyrene ultrathin films were selectively formed on lyophilic areas.
Sen'i Gakkaishi, 1986
The fatigue behavior of solid-state extruded high-density polyethylene (HDPE) was investigated on... more The fatigue behavior of solid-state extruded high-density polyethylene (HDPE) was investigated on the basis of dynamic viscoelastic measurements during the fatigue process. It was observed that
Journal of The Adhesion Society of Japan, 2007
Nihon Reoroji Gakkaishi, 2008
Scanning viscoelasticity microscopy (SVM) with a mechanical model analysis was applied to polysty... more Scanning viscoelasticity microscopy (SVM) with a mechanical model analysis was applied to polystyrene (PS) surfaces. When the surface was in a glassy state, that is, in an elastic regime, the SVM vibrational system can be simply expressed by a series model composed of two springs such as a cantilever and the sample surface. Once the surface reaches in a viscoelastic regime, a damping factor must be incorporated into the model surface. The spring constants for the PS surfaces being in glassy and transition states were successfully extracted by the analysis. The surface value even for the glassy state was lower than the corresponding bulk value by a few decades.
RSC Advances, 2015
Poly(dimethylsiloxane) (PDMS) surface was patterned by poly(2-methacryloyloxyethyl phosphorylchol... more Poly(dimethylsiloxane) (PDMS) surface was patterned by poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-containing photo-crosslinking diblock copolymers upon photo-irradiation.
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Papers by Atsushi Takahara