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Linear polysiloxanes were synthesized by using organometallic carboxylic acid catalysts containing tin, zinc, or iron. By optimizing the amount of catalyst and the reaction temperature, polysiloxan...

We prepared a dielectric elastomer actuator composed of hydrogenated carboxylated acrylonitrile-butadiene rubber (HXNBR)/nitrile group (CN)-modified and non-modified titanium oxide (TiO2) particles with insulation properties. The CN group-containing silane coupling agent was synthesized via a thiol–ene reaction between acrylonitrile and 3-mercaptpropyltrimethoxysilane and immobilized onto the TiO2 particle surface. The HXNBR/CN-modified and non-modified TiO2 particle composite elastomer showed a high relative dielectric constant and generated stress in a low electric field. The relative dielectric constant increased proportionally with the amount of CN-modified TiO2 particles, showing a value of 22 at 100 Hz. As the dielectric constant increased, the volumetric resistivity decreased; however, the dielectric breakdown strength was maintained at 95 V/mm. The generated stress of the composite elastomer increased in proportion to the relative dielectric constant, showing a maximum of 1.9 MPa. The card-house structure of TiO2 particles in the composite elastomer is assumed to suppress the dielectric breakdown in a low electric field. Thus, we demonstrated that an elastomer containing a high dipole group on an insulating particle surface is capable of improving the power performance of soft actuators.

We synthesized silica-coated barium titanate (BaTiO3) particles with different silica shell thicknesses and evaluated the effect of silica coating on the relative dielectric properties of silica-coated BaTiO3 particles. Furthermore, composite elastomers were prepared using hydrogenated carboxylated acrylonitrile-butadiene rubber (HXNBR) with a high relative dielectric constant (er) and silica-coated BaTiO3 particles, and their performance as an actuator was evaluated. Both er and relative dielectric loss of non-coated BaTiO3 particles increased at low frequencies (

We synthesized rubbers including cyanoethyl groups and evaluated the effect of side-chain structures on dielectric properties, electrical properties at room temperature, and glass-transition temper...

Acrylonitrile-butadiene rubbers (NBRs) have a lower glass transition temperature (T g) and a higher dielectric constant than other rubbers. To understand how a low T g and a high dielectric constant are compatible, we focused on the acrylonitrile (AN) monomer sequence in rubber and synthesized random and alternating copolymers to evaluate the effect of the sequence. The AN monomer sequence dependence of the relative dielectric constant was investigated by the C-N stretching vibration of the nitrile group through Fourier transform infrared spectroscopy and internal rotation potential energy measurements around the C-C bond within the nitrile group based on dimer model calculations. The alternating copolymers, including NBR, showed a higher dielectric constant than random copolymers. The alternating copolymer shifted from ∼2243 cm-1 for polyAN to ∼2236 cm-1 for NBRs, while the random copolymer only shifted to ∼2239 cm-1. The peak of the C-N stretching vibration was correlated with the AN sequence. The sequence dependence of the shift can be explained by the C-N bond length calculation. The internal rotation potential energy between gauche and trans of the NBR model was the lowest, indicating that the NBR main chain is flexible and that AN in the main chain rotates easily. Therefore, NBR has a high dielectric constant and a low T g because of the presence of an alternating sequence and the flexibility of the NBR main chain.

Ionic liquid monomers with ion pair interaction energies ranging from 73.0 to 101.4 kcal/mol were designed by using the calculated electrostatic potential (ESP) values of the component ions. The io...

ポリフッ化ビニリデン(PVDF)とポリメチルメタクリレート(PMMA)を用いたポリーアロイは相溶性を有する系として現在に至るまて数多くの研究が行われているが, 今回置換基の異なる3種のポリアクリル酸エステルを用い, PVDFとの相溶性あるいは結晶化速度等を検討した結果, メチル置換基ではPMMAと同様相溶性を有することがわかりプチル置換基となるに従って非相溶領域(液液相分離)が増大することを見出した. また, PVDFの球晶成長速度はポリアクリル酸エステルの混合量および過冷却度に大きく依存し, Hoffman-Lauritzen 理論に従って進行することがわかった. 一方, 二軸押出機を用いた混練物の強度特性および誘電率特性は, PVDFの結晶化度に大きく依存することを見出した.

金属表面と加硫ゴムの固着は両者の界面で起こる物理的な吸着とその後に起こる一次結合の生成によるので, ゴムにブルーム剤を添加して両者間に低エネルギー表面のブルーム薄膜を生成させて隔離することにより固着が防止できることがわかった. 固着防止効果はブルーム剤の種類, 添加量, 加硫配合剤, 及び固着試験温度の影響を受けた. 固着防止効果のあるブルーム剤は無極性の長鎖アルキル基と極性の酸アミド基からなる基本構造を有し, ブルームするに適当な融点, 分子量, 及び溶解性をもつことが必要であった. 一般に, 添加量の増加とともに固着強度は減少するが, 充分な隔離効果を発揮させるためには大体4部以上のブルーム剤の添加が必要であった. 加硫剤, 加硫促進剤, 安定剤, 可塑剤などの加硫配合剤はブルーム剤の融点降下の作用をするためブルーム速度を増加させる固着防止にプラスの作用と, 生成したブルーム薄膜の機械的強度を低下させる固着防止にマイナスの作用のあることが明らかとなった. ブルーム剤の選択は固着試験温度を考慮して行われるべきであり, 試験温度よりその融点が20～30度高いブルーム剤を選ぶことが必要である. ブルーム薄膜の構造解析とSEM観察から固着防止に有効なブルーム薄膜の構造に二種類あることが明らかとなった.