Published papers

The free-radical polymerization of vinyl pentafluorobenzoate (VPBz) was carried out under various conditions in order to compare its stereochemistry to that of the vinyl benzoate (VBz) polymerization using similar conditions. Contrary to the stereochemistry of the radical polymerization of VBz, VPBz favors syndiotactic propagation. The poly(VPBz) obtained in hexafluoroisopropanol (HFIP) with nBu3B–air at −30 °C has a triad syndiotacticity (rr) of 52% which achieved the highest syndiotacticity reported for the radical polymerization of vinyl esters. The stereochemistry difference for the VPBz polymerization was ascribed to the electron-withdrawing effect of the fluorine on the aromatic ring. The solvent effect of enhancing the rr specificity in HFIP may be related to the hydrogen-bonding between HFIP and VPBz or the growing species. It was also found that the glass transition temperatures (Tg) of the VPBz polymers apparently increased with an increase in their diad syndiotacticities (r): the Tg of poly(VPBz) with r=72% was 79 °C, which was 25 °C higher than that of poly(VPBz) with r=56% obtained in toluene.

複屈折性結晶により、世界で初めて光学ポリマーの複屈折を相殺したことについて、その原理，学術的意義および工業的意義について平易に紹介する。

A method for reducing the orientational birefringence of polymers by doping with optically isotropic silica particles is reported. Particles with a diameter of 16 nm were selected and their surface was treated with dimethyldichlorosilane. Doping with 1 wt% of the particles reduced about 15% of the orientational birefringence of polycarbonate and poly(methylmethacrylate) films regardless of the sign and the magnitude of their birefringence. The analysis of the infrared dichroic ratio confirmed an effect in which the particles reduced the orientation of polycarbonate main chains. The effect that caused the reduction of birefringence was named "the orientation-inhibition effect."

ブロードバンド社会を拓くフォトニクスポリマーについて「伝送とディスプレイ」という切り口で解説した

Birefringence induced by the orientation of polymer mainchains during an injection- molding or extrusion processing restricts the application of optical polymer to optical devices that require maintaining the polarization state of incident light. We propose the "birefringent crystal dopant method" to compensate the birefringence of polymers by homgeneous doping with an opposite birefringent needle-like crystal. SrCO3 was selected for this method and synthesised, with a length of about 200nm and a width of about 20nm. SrCO3 was doped into PMMA/BzMA film. The film was uniaxcially drawn at 130℃ and 4mm/min. For the first time, the positive birefringence of the drawn coplymer film at a wavelength of 633nm was compensated by doing with 0.3we.% of SrCO3 without losing transparency and thermostability. The orientational birefringence of the zero-birefringence film was lower than that of blank copolymer film at any angle of incidence of light.

ポリマー鎖が配向しても複屈折性が生じない「ゼロ複屈折性光学ポリマー」という概念とその有用性について述べ、ゼロ複屈折性光学ポリマーを実現するために新たに提案した「複屈折性結晶ドープ法」について紹介した。

ハードのブロードバンド化を達成しうる通信メディアとして近年注目されているPOFについて解説した。

Fluorinated polymers have become of increasing interest in the development of advanced materials having superior thermal and chemical stability, excellent electrical insulating ability, and unique optical properties. Perfluoropolymers such as Teflon AF and Cytop have been commercialized by DuPont and Asahi Glass, respectively.2,3 These polymers have high chemical and thermal stability and are soluble in selected fluorinated solvents. However, the polymers are quite expensive due to the high manufacturing costs for their monomers.3 Here, we report that a partially fluorinated polymer, poly(2-difluoromethylene-1,3-dioxolane) (P1), is thermally and chemically stable and is soluble in fluorinated alcohols.

近年、従来の金属線と同様な取扱い性を有しながらギガビット以上の伝送を可能とする高速プラスチック光ファイバー（POF）に新たな注目が寄せられている。ビデオをレンタルしないで家庭にいながらのダウンロード、臨場感あるリアルタイム動画伝送など、ギガビット光ファイバー網が可能とする膨大な新しい光通信技術を展望する

当研究室では、複屈折ゼロの光学ポリマーを開発した。この光学ポリマーで最も重要視されるのが複屈折の低減である。複屈折ゼロの光学ポリマーは世界でも初めてである。このポリマーの研究開発のを狙いとその背景、特徴、今後の展望を含めて紹介した。

It was shown how high mechanical strength should be provided in the high numerical aperture (NA) graded-index plastic optical fiber (GI POF). In this newly developed GI POF, a copolymer of methyl methacrylate (MMA) and 2,2,2-trifluoroethyl methacrylate (3FMA) was used to increase the NA. The GI POF we proposed previously was composed of a PMMA homopolymer cladding and a doped PMMA core. It was previously shown that substituting the copolymer P(MMA-3FMA) for the PMMA as the cladding material made little change in the fiber's light-transmission characteristics. This study focused on mechanical flexibility, which is one of the most important advantages of the POF. It was found that the P(MMA-3FMA)-clad GI POF had almost the same or superior mechanical strength in addition to the excellent light-propagation characteristics. It was also found that such excellent mechanical properties were achieved using a small dopant concentration and optimum heat-drawing conditions.

A doped poly(methyl methacrylate) (PMMA)-based graded-index plastic optical fiber (GI POF) with high mechanical strength is reported for the first time. Although the POF is generally believed to have a good mechanical flexibility even if it has a large-core diameter, such a high mechanical strength has been provided by making the polymer chains in the POF highly oriented in its axial direction. If such an orientation of polymer chains is eliminated, the POF becomes brittle, which is similar to silica-based fibers. On the other hand, too high an orientation of the polymer chains induces fiber deformation in a high-temperature atmosphere resulting from orientation relaxation. This study reports how high mechanical strengths such as the tensile strength and the large elongation are provided to the GI POF. By selecting the optimum heat-drawing conditions, the GI POF has a mechanical strength comparable to that of the commercially available step index (SI) POF.

低コストで光情報化が可能な高速プラスチック光ファイバーとそのネットワークについて紹介した。更にそれがもたらす現在のインターネットの延長でないリアルタイムのフェイストゥフェイスコミュニケーションの生活と社会のあり方について説明した。

A novel perfluoromonomer, perfluoro-2,3-dihydro-1,4-benzodioxin (FDB), was synthesized. The homopolymerization and copolymerizations of FDB were investigated. The structure and physical properties of those polymers were characterized.

A relation between the -3 dB bandwidths of graded-index plastic optical fibers (GI POFs) and the total power penalty of 50-m GI POF links is investigated in detail. The bandwidth of the GI POF is deliberately varied by controlling the index profile. It is theoretically and experimentally confirmed that sufficiently high bandwidth on the order of gigahertz is necessary for the GI POF, even for several hundreds of megabit per second (Mb/s) data rate, in order to achieve the power penalty free in the bit error rate performance of the link. In the case of silica-based multimode fiber links, it has been reported that the launch condition strongly affects the bit error rate performances; hence, a special launching technology for the silica-based multimode fiber is developed to achieve a 1-Gb/s transmission in the gigabit Ethernet protocol. In this paper, it is also found that the power penalty-free state is realized in the GI POF link, which is independent of the launch condition, when a GI POF with a nearly ideal index profile is used. The GI POF is a promising physical layer for realizing stable, high-speed and low-cost data-com networks.

これまで行ってきた研究成果を光の偏波（またはフォトン）と高分子物質との係わりという視点で原子系のディメンジョンからマクロな不均質構造にわたって順に述べた。

これまで行ってきた研究成果を光の偏波（またはフォトン）と高分子物質との係わりという視点で原子系のディメンジョンからマクロな不均質構造にわたって順に述べた。

We have developed a highly scattering optical transmission (HSOT) polymer, and have succeeded in applying it to a highly efficient backlight light guide in liquid crystal displays (LCDs). In the present work, a multiple scattering modeling simulation has been developed. Also the effects of adjacent particles inside the HSOT polymer are demonstrated. The numerical calculation, improved by taking account of the adjacent particles, has precisely reproduced the multiple scattering phenomena inside the HSOT polymer. Based upon the results of the multiple scattering analyses, an optimal design has been developed and applied to an LCD backlighting system. By altering the internal particle conditions, uniformity of color and brightness on the top face of the backlight has been achieved.

We propose a highly-efficient backlight that requires no optical films with a polymer containing spherical particles of micron size. The developed backlight is provided with microprisms at the bottom surface, which can reflect directly the incident light into the front direction. The modeling simulation program, employing a Monte Carlo method based on Mie scattering theory, has optimized both the prismatic condition and the multiple scattering characteristics. We confirm that a uniformity of brightness can be achieved without using any optical films, resulting in a high optical efficiency of 62%.