Tomokazu Iyoda

Charge-controllable polypyrrole/polyelectrolyte composite membranes: Part II. Effect of incorporated anion size on the electrochemical oxidation-reduction process

Abstract Polypyrrole (PPy) films with various electrolyte anions were prepared by electropolymerization of pyrrole (py)in water. While the anodic doping process in the electropolymerization of py was scarcely affected by the size of the electrolyte anion, the oxidation-reduction (doping-undoping) process in the resulting PPy was influenced largely by the size of the incorporated anion (the dopant anion). Especially, an anionic polyelectrolyte (PE, an immobilized polymer dopant) incorporated in PPy was not released from the PPy matrix even when PPy was reduced electrochemically. The electroneutrality of PPy/PE (PE-incorporated PPy) was conserved by penetration of the electrolyte cation into the PPy matrix (pseudo-cathodic doping). The fixed charge polarity in PPy/PE was inverted reversibly between the positive and negative sign through the oxidation and the reduction of PPy. The PPy/PE composite acted as a “charge-controllable membrane”.

Syntheses of conducting polymer Langmuir-Blodgett multilayers

Abstract Three types of method for the preparation of conducting polymer Langmuir-Blodgett (LB) films with high conductive anisotropy are demonstrated. The resulting LB multilayers of polypyrrole derivatives and a polyaniline derivative exhibit anisotropic conductivity due to the alternating layered structure ofsb conducting polymer layers and insulating alkyl or perfluoroalkyl chain layers.

Conducting polymer electrodes with high performances through anodic doping process

Abstract A novel approach to functionalize conducting polymer electrodes is developed through anodic doping process. Every negatively-charged functional molecule is efficiently incorporated into conducting polymer matrix on electro-polymerization. The resulting conducting polymer electrodes show a wide variety of high performances responsible for the functional molecules.

A novel anisotropic conducting thin film having a conducting and insulating layered structure

Electrochemical polymerization of Langmuir-Blodgett multilayers of amphiphilic pyrrole derivatives resulted in novel anisotropic conducting thin films (T. Iyoda, M. Ando, T. Kaneko, A. Ohtani, T. Shimidzu and K. Honda, Tetrahedron Lett., 27 (1986) 5633). They have an alternating layered structure of a conducting polypyrrole layer and an insulating alkyl chain layer. This paper deals with their syntheses, characterizations and functionalities.

Electrochemical polymerization in Langmuir-Blodgett film of new amphiphilic pyrrole derivatives

Abstract Electrochemical polymerization in Langmuir-Blodgett multilayers of amphiphilic pyrrole derivatives resulted in anisotropic conducting thin films having alternate conducting and insulating layered structure.

A multi-mode chemical transducer 1 new conjugated function of photochromism and electrochromism of azo-quinone compound

Abstract A new class of chemical transducer, azo-quinone (1) shows both electrochromism and photochromism. Moreover, the rate of thermal decay of cis-form was dependent on quinone region.

Functionalizations of Conducting Polymers by Mesoscopically Structural Control and by Molecular Combination of Reactive Moiety

This paper contains the following three subjects; (1) in situ fabrication of mesoscopic conducting polymer heterolayers superlattice, (2) functional molecular materials constructions by incorporation of the functional molecule to conducting polymer, (3) one-dimensional photoactive molecule linked with conducting molecular wire. (1) A novel potential programmed electropolymerization method which enables us to fabricate any microscopic depth structures in conducting polymer ultrathin films, such as heterolayers and sloped layers, has been developed. The depth profiles of the heterolayers such as thickness and polymer composition are controlled by applied electrode potential, and not only nanometer order layered structures but also sloped ones have been easily synthesized. Accordingly, this method is aimed at manipulating electric, optical and other various properties specific to the depth structure by changing structural parameters such as polymer composition or doping level of the layers, finally to realize an organic superlattice such as type I and type II heterostructures Esaki et al proposed1). Here, an organic superlattice having the structure-specific properties, including a quantum size effect was realized. (2) By the electrochemical polymerization and/or doping methods, conducting polymers incorporating functional molecules which show the specific function attributed, to the incorporated molecule were presented. (3) One-dimensional phosphorus(V)porphyrin polymers linked with the various length of oligothienyl molecular wire toward the axial direction of the porphyrin ring were synthesized from symmetrical phosphorus(V)porphyrin triads with two oligothienyl axial groups. In the polymers, the phosphorus(V)porphyrin unit which tends to be an electron acceptor acted as a photoinduced hole generator, and the oligothienyl moiety which tends to be an electron donor was able to transfer the positive hole just as molecular electric wire. The conductivity of these donor-acceptor polymers was strongly enhanced by the photoirradiation, indicating that the photoinduced carrier formation and transfer occurs efficiently along the polymeric chain.

Optical properties of conjugated polymer superlattices prepared by potential‐programmed electropolymerization

Photoluminescence (PL) spectra of thin films of pyrrole and bithiophene copolymer with an alternating layered structure prepared by the potential‐programmed electropolymerization method were investigated. Band edges of thin films of the copolymers were estimated by optical and electrochemical method, and they were adopted to design a superlattice potential profile of the alternating layered film. PL spectra of the copolymer films shifted to higher energies as thiophene fraction in the film decreased. This shift corresponded to band structure change. PL spectra of the layered films, designed to be type II superlattices structure, shifted to higher energies as periodicity of the layered structure became shorter. This phenomenon is to be interpreted as a quantum size effect. The observed shift was explained by the Kronig–Penney model with 0.6me (electron mass) of effective mass.

Preparation and properties of amphiphilic polythiophene Langmuir-Blodgett films

Abstract Newly synthesized amphiphilic polythiophene, poly(heptadecyl 3-thiopheneacetate), formed a stable condensed monolayer on pure water, whether it was oligomer or high-polymer type. The monolayer was accumulated as a Z-type film onto a hydrophobic substrate by the vertical dipping method. For the Langmuir-Blodgett (LB) film composed of oligomer, a layered structure of polythiophene backbone layers and alkyl chain layers accumulated alternately, as ascertained by X-ray diffraction and transmission electron microscopy. The LB film composed of high-polymer showed photoluminescence originating in undoped polythiophene at room temperature.

Some aspects of electron transfer sensitization systems

Some aspects of electron transfer sensitization systems not only for chemical conversion and storage of light energy but also for design of photoelectrochemical molecular device are presented. Also regarding energy conversion as one of chemical transformation of every chemical signal (information), we have been introducing and realizing the concepts of molecular electronic device. This paper involves 4 subjects for the former and 2 subjects for the latter. (1) Visible-light-induced water reduction with dye-sensitized semiconductor powder catalysts. (2) Regulation of photo-redox cycle of of water-soluble metalloporphyrins. (3) Electron transfer of the excited triplet state of water-soluble palladium porphyrins. (4) Photo-induced electron transfer of accordion- type porphyrin cluster. (5) Materialization of photo-active functional molecules with conducting polymer matrices. (6) Multi-mode chemical signal transducer.