Redox polymers based on the poly(vinylpyridine) complex of [Os(bpy) 2 Cl] +/2+ were quaternized with methyl iodide, and the quaternized polymers were used to "wire" glucose oxidase. Quaternization enhanced both the rate of electron transport in cross-linked redox hydrogels containing glucose oxidase and the strength of the electrostatic complex formed between the polycationic redox polymer and the polyanionic glucose oxidase. Quaternization with methyl groups also decreased the number of pyridine rings available for cross-linking by the water soluble cross-linker poly(ethylene glycol) diglycidyl ether. The current densities of glucose electrooxidation increased with the degree of quaternization of the "wires" until one-third of the pyridine rings were quaternized, and the activation energies decreased until one-half of the rings were quaternized.

We describe here a polymer nanosheet assembly that serves as a molecular photoswitching and optical exclusive OR (EXOR) logic gate. Separate polymer nanosheets (monolayers) containing phenanthrene, anthracene, and dinitrobenzene chromophore were prepared by the Langmuir-Blodgett technique (LB films). A bilayer-couple, consisting of phenanthrene (sensitizer) monolayer and dinitrobenzene (acceptor) monolayer, and the other couple, of anthracene monolayer and dinitrobenzene monolayer, were confirmed to function as a photodiode showing current rectification on light irradiation. The two photodiodes are connected as each photocurrent direction becomes opposite. In the polymer photodiode array (LB films), anodic photocurrent was observed when the anthracene was selectively excited. On the other hand, cathodic photocurrent was observed by selective excitation of the phenanthrene. Moreover, the output photocurrent displayed a very small value when the phenanthrene and anthracene were excited simultaneously. The performance is discussed for this gate's application to an optical EXOR logic gate.

Semiconducting thin films consisting of regioregular poly(3-hexylthiophene) (RR-PHT) and poly(N-dodecylacrylamide) (pDDA) were constructed by the Langmuir-Blodgett (LB) technique. A mixture of RR-PHT and pDDA spread from a chloroform solution on a water surface forms a stable monolayer, which can be transferred onto solid substrates by the LB method, yielding a well-defined polymer LB film. Surface morphology studies of the LB film indicate that the RR-PHT is dispersed uniformly throughout the surface. The polymer thin film was chemically doped by contacting with FeCl3 acetonitrile solution, and a conductivity of 5.6 S/cm was achieved. Further, the LB film was utilized as the semiconducting film in the field-effect transistor (FET), and mobilities of 2.2 x 10(-4) and 4.4 x 10(-4) cm2 V(-1) s(-1) were obtained by analyzing the saturated and linear regions of the current-voltage characteristic, respectively.

This paper describes effective photocurrent generation based on a polymer Langmuir−Blodgett (LB) monolayer containing ruthenium complex on a silver electrode excited by surface plasmon resonance (SPR). It was found that photocurrent generation is greatly enhanced at an incident angle where the electromagnetic field was most enhanced by SPR. At this angle, the photocurrent is enhanced by a factor of 23.6 compared with that at the critical angle for total internal reflection. The incident monochromatic photon-to-current conversion efficiency was 9.53 × 10-3%, higher than that of the corresponding polymer LB monolayer film on a transparent indium tin oxide electrode with conventional direct transmitted light (2.87 × 10-3%). Furthermore, it was demonstrated that precoating with poly(N-dodecylacrylamide) homopolymer ensures adequate separation of the Ru(bpy)3 2+ and silver surface, thereby suppressing the quenching of photoexcited Ru(bpy)3 2+ by the silver. Controlling the distance between the Ru(bpy)3 2+ layer and the silver using the Langmuir−Blodgett technique leads to effective photoexcitation of Ru(bpy)3 2+ by SPR and suppression of quenching by the silver surface, resulting in efficient photocurrent generation.

The spreading behavior of monolayers of poly(N-(polyfluoroalkyl)acrylamide)s having various fluorocarbon chain lengths at the air−water interface was investigated by measurement of surface pressure−surface area isotherms to prepare fluorinated polymer LB films. The monolayer properties strongly depend on the length of the fluorocarbon chains. The monolayer of N-(1H,1H-heptafluorobutyl)acrylamide polymer (C3F7AA) formed an expanded monolayer, N-(1H,1H-pentadecafluorooctyl)acrylamide polymer (C7F15AA) and (2-(perfluorooctyl)ethyl)acrylamide polymers (C8F17AA) formed liquidlike fluid condensed monolayers, and the (2-(perfluorodecyl)ethyl)acrylamide (C10F21AA) monolayer was rigid crystalline. The polymer monolayers except C10F21AA can be transferred onto solid substrates, and uniform polymer LB films can be prepared. The wettability and the surface structure of the LB films were also investigated by measuring the static contact angle (θ) of water on the surface. The surface structure was discussed from the critical surface tension, which was estimated by measuring the contact angles of several n-alkanes on the film surface.