Fabrication of Anisotropic Polypyrrole Actuators

The novel features of electrochemical actuators fabricated from a cylindrical polypyrrole (PPy) pipe prepared by the electrochemical polymerization techniques have been described. This cylindrical PPy pipe was cut into a rectangular film and its electrochemical and electrical properties were measured. When the inner surface of the PPy film (surface in contact with electrolyte when PPy was polymerized) was insulated and redox was carried out, the PPy film bent toward the outer surface (surface in contact with a slender Teflon pipe when PPy was polymerized) upon reduction and returned to its original shape upon oxidation. However, the bending was not completely accompanished by redox when the outer wall side of the PPy film was insulated. Although such an anomalous bending in the PPy film actuator cannot be explained satisfactorily at this stage, we speculate that the bending phenomena are due to steric effects from cation insertion and extraction

ハンノウ カガクシュ ノ デンキョク ヒョウメン ヘノ キュウチャク ニヨル デンキ カガクテキ オウトウ

電子やイオンの流れを利用した生物の裔度なメカニズムを解明する「生物電気化学」では、温和な条件下で酵素などの生体関連物質の電気化学反応を実現できるため、バイオセンサやバイオ燃料電池への展開が可能で、電極の触媒機能を分析する最良の方法はおそらくサイクリックボルタンメトリである。リン酸緩衝液(PBS) 中で、電極としてボールミルで粉砕処理したグラファイト(pGr) を使用して、ドーパミン(DA) のサイクリックボルタモグラムを測定すると、末処理グラファイト電極の場合に比べて酸化還元ピークの増強をもたらす。DAのピーク電流は、粉砕時間などの前処理条件に大きく影響する。電極反応をスムースに進行させる効果（電極触媒効果）は、pGrの被覆によるガラシーカーボン電極(GCE)表面の粗面化が強調されることによる。つまり、粉砕や電解処理により、pGr表面にカルボニル基(C=O)、カルボキシ基(-COOH)、エポキシドなどが導入されていると考えられ、酸化還元反応の触媒として作用し、さらにベンゼン環表面のスタッキング、pGrとDAのπ-π相互作用、水素結合などが関与していると考えられる。また、これらのことは、PBS (H_3PO_4) の電気化学的現象であるため、pGr表面にリン酸基(H_2PO_4^-、HPO_4^{2-}、PO_4^{3-}）などの化学種が導入されることも予想される。一方、このような電流応答特性の掃引速度依存性において、ピーク電流値（酸化ピーク、Ipaおよび還元ピーク、Ipc) と掃引速度との間に線形関係が認められ、電気化学の基本方程式であるネルンストの式から、電極活性種(DA)の電極表面への吸着が示唆され、表面吸着制御機構の電極反応と考える。In "bioelectrochemistry", which elucidates the advanced mechanism of living organisms that utilize the flow of electrons and ions, it is possible to realize the electrochemical reaction of biological-related substances such as enzymes under mild conditions, so expansion to biosensors and bio-fuel cells, etc. is being considered, and the best method for analyzing electrode catalytic function is probably cyclic voltammet1-y. In phosphate buffer solution, pretreatment of graphite crushed using a ball mill (pulverized graphite, pGr) as an electrode resulted in enhancement of the redox peaks of dopamine (DA) on its cyclic voltammogram. The peak current of DA was appreciably affected by the experimental conditions at pretreatment such as pulverized time. The effect of enhancing the current response (electrode catalytic effect) is that the roughening of the glassy carbon electrode (GCE) surface is emphasized due to the coating of pGr by the pulverization treatment of graphite. That is, it is considered that carbonyl group (C=O), carboxy group (-COOH), epoxide, etc. introduced into the pGr surface due to pulverization or electrolysis treatment, moreover, stacking of benzene ring surface, π-π interactionbetween pGr and DA, hydrogen bond, etc. are involved as catalysts for redox reaction of DA. In addition, as these mentioned above are an electrochemical phenomenon in PBS (H_3P0_4), it is expected that chemical species such as phosphate groups (H_2PO_4^-, HPO_4^{2-}，PO_4^{3-}) will be introduced on the pGr surface. On the other hand, in the sweep rate dependence of such current response characteristics, if there is a linear relationship between the peak current values (oxidation peak, Ipa and reduction peak, Ipc) and the sweep rate, from the Nemst equation which is the basic equation in electrochemistry, the electrode active species (DA) is suggested to be adsorbed on the electrode surface, and is considered to be an index of the surface adsorption control mechanism