We have studied the surface morphology of free standing single crystals of thermochromic polydiacetylenes (PDAs), namely, ETCD and IPUDO (respectively, the ethyl and isopropyl urethanes of 5,7-dodecadiyn-1,12-diol), by Atomic Force Microscopy (AFM) under ambient conditions. Micron scale as well as molecularly resolved images were obtained. The micron scale images indicate a variable surface, and the molecularly resolved images show a well defined 2-D lattice that is interpreted in terms of molecular models and known crystallographic data. Thereby information about surface morphology, which is crucial to potential optical device or chromic sensor performance is available. We also report the observation of a “macroscopic shattering” of the IPUDO monomer crystal during in-situ UV polymerization studies.

The copolymerization of 3-alkylthiophene and 3,4-dialkylthiophene units in well defined ratios leads to materials in which it is possible to modulate continuously the electronic properties such as the conjugation length and the energy-gap. The soluble materials have optical properties depending on the chemical composition of the chain. A macromolecular and optical characterisation has been performed on two copolymer series.

Nanometric gold particles were synthesized by a liquid/liquid phase-transfer reaction. Composites of these particles in polystyrene, poly(methyl methacrylate) and poly(phenylmethylsilane) were prepared at concentrations from 1.0 to 5.0 mg/ml were prepared, with no noticeable agglomeration of particles during processing. These materials showed a linear absorption peak at 530 nm, which is characteristic of nanosized gold. Highresolution electron microscopy measurement showed that the particle diameters were approximately 2.2 ± 1.3 nm. Degenerate four-wave mixing experiments at 532 nm yielded, on 10-micron films, a maximum value of 1.5 × 10−10 e.s.u. for the third-order nonlinear optical susceptibility.

Macrocyclic bis-dienes and a diendienophile were prepared in Diels-Alder reactions starting from the bis-dienophilic (hemiporphyrazinato)nickel complex 1. 1 was reacted either with the tetraene 2 or with tetraphenylcyclopentadienone (4). By combination of macrocyclic bisdienes and bis-dienophiles, ladder-type oligomers were synthesized. They are precursors to the corresponding conjugated molecules, which are of interest as potential organic conductors. Monofunctional and bifunctional dienophilic macrocycles were also allowed to react with [60]fullerene to give the corresponding mono- and bis-fullerene adducts.

The water-soluble self-acid-doped conducting polyanilines, poly(aniline-co-Npropanesulfonic acid aniline) (PAPSAH) and sulfonic acid ring substituted polyaniline (SPAN), in aqueous solutions at full concentration range are characterized. The PAPSAH and SPAN can be cast into free standing films from their aqueous solutions and have the doping level, about 0.3. Their conductivities at room temperature are about the same (10−2 S/cm). As temperature increases, conductivities of PAPSAH and SPAN increase to the maxima about 10−1 S/cm at 110°C and 190°C respectively. Above these temperatures, their conductivities drop resulting from thermal undoping accompanying with a loss of some polarons. The incorporation of PVA into PAPSAH and SPAN provides excellent flexibility and only slightly decreased conductivity (10−3 S/cm at equal weight %). Applications of these two polymers and their blends in electron beam lithography and light emitting diode are studied.

A new soluble and dopable copolymer consisting of 3‘,4‘-dibutyl-2,2‘:5‘,2”-terthiophene and phenylene vinylene units has been designed and prepared via a Wittig reaction. This copolymer is soluble in common organic solvents such as THF and CHC13, and can be doped with various oxidants increasing its electrical conductivity by several orders of magnitude. Its films are electrochromic and turn reversibly and rapidly from red to green-blue upon doping and undoping electrochemically. If the phenylene vinylene units are replaced with phenylene imine units, another interesting new polymer forms which is not readily dopable with the same oxidants but is dopable with acids. The new material exhibits strong chemochromism with dramatic shifts in its optical absorption spectra. In the undoped state both copolymers show strong photoluminescence.

CW absorption and emission spectra as well as time-resolved photoemission dynamics have been employed to detect the evolution of the first excited electronic states and the associated spectroscopical changes in passing from the isolated molecules to the aggregated state in thiophene oligomers. To this end a novel form of inclusion compound in PHTP in which the molecules are electronically decoupled in the solid state has been studied, thus avoiding the complications associated with the change in conformation occurring upon dissolution. The experimental data are interpreted in terms of the molecular exciton model.

Solutions of Ag(I) and poly(3-alkylthiophenes), which usually precipitate immediately upon contact, are stabilized with Ag(l)-coordinating ligands. Casting of polymer-Ag(I)-ligand solutions followed by evaporation of the ligand yields an electronically conducting polymer film. It is postulated that Ag(I) either undergoes nucleophillic addition to poly(3-alkylthiophenes), in a manner similar to which polythiophenes are protonated by acids, or forms a charge transfer complex with the polymer. The “doped” polymer exhibits enhanced stability over films oxidized using conventional oxidants. Ag(I)-doping of poly(3-alkylthiophenes) represents a new strategy for doping conjugated systems.

Solutions of emeraldine base(EB) in DMPU have been successfully spun into fibers and characterized according to their morphology, mechanical and electrical properties. This study presents results for as-spun (undrawn) fibers. The viscoelastic behavior of EB spin solutions have been investigated with dynamic measurements of the complex moduli, first normal stress coefficient, and complex viscosity. A knowledge of the viscoelastic behavior of emeraldine base solutions is crucial for effective processing into fibers and films.

A new approach for the synthesis of poly(phenylenimines) and related conjugated polymers is presented. A novel bifunctional monomer, N-Boc-indoaniline 4 is synthesized as shown in scheme I. Thermolysis of the latter, either as solid, thin film or in solution of high boiling solvents, leads to polycondensation of the bifucntional monomer and results in the formation of poly(phenyleneimine) or its reduced form. Scope and limitation of this approach in the synthesis of various poly(aryleneimines) is also described.

We report a study of the electrical and optical properties of thin films of tetraanilinobenzene (TAB) and polyaniline (PANI) deposited using the Langmuir-Blodgett (LB), layer-by-layer selfassembly and vacuum-evaporation techniques. The paper will mainly concentrate on TAB LB films, but also results for other films are presented for comparison. The optical studies of undoped TAB LB films indicate H-aggregates. Upon doping new polaronic absorption bands appear and the photoluminescence of TAB becomes quenched. Doped LB and self-assembled films can reach conductivities up to about 10−4/cm for TAB and a few S/cm for PANT. The conductivity has a temperature dependence logσ α T−1/2, suggesting variable-range hopping in a quasi-gap, possibly due to the Coulomb interactions between localized carriers.

Current corrosion control methods use coatings which are toxic and environmentally hazardous materials, such as, chromium. More work needs to be done to find a substitute that is competitive with current industrial technologies. Many polymeric materials have been tested as possible alternatives to the present systems. These include polysiloxanes, polymer blends based on polymethylmethacrylate/polysiloxanes and co-polymers of these materials. [1] Oxidized and carbided metal surfaces have been analyzed as chromium substitutes as well. [2] So far the technology has not advanced to a industrially competitive level. Polyaniline is on of the most promising materials for environmentally safe corrosion control.

We report the corrosion protection properties of a novel conductive polymer coating on aluminum alloys. The conductive polymer coating is a double strand molecular complex of polyaniline and a polyelectrolyte. The double strand polyaniline offers advantages in stability and processability over other forms of conductive polymers. The coated aluminum alloys (AA7075- T6) were evaluated for corrosion protection in an aggressive salt environment of.5N NaCl solutions using cyclic polarization and electrochemical impedance spectroscopy. Corrosion current densities were calculated for uncoated alloy samples and alloys coated with the conductive and non-conductive derivative of the double strand polymer. The conductive form of the double strand polyaniline coating shows a two order of magnitude lowering of the corrosion current over the uncoated samples and a one order magnitude lowering over the non-conductive form of the polymer coated samples. The shape of the cyclic polarization data closely resembles results of sulfuric acid anodized aluminum. This data indicates that the conductive state of the polymer is required for improved corrosion protection and an anodized type protection is occurring.

When thin films of polyaniline (emeraldine base, EB) are deposited on glass substrates from aqueous solutions of polymerizing aniline (“in-situ” EB-I film), they exhibit a Vis/UV spectrum in which the exciton peak has an absorption maximum at ∼600 nm; exposure to NMP vapor results in a shift of this peak to ∼650 nm (EB-II film). Doping of EBI film by aq. HCl gives the characteristic Vis/UV spectrum of “tight coil” doped polyaniline with a localized polaron peak at ∼820 nm. Treatment of EB-II film with HCl in a similar manner gives the characteristic spectrum of “expanded coil” doped polyaniline in which the ∼820 nm peak has disappeared and is replaced by a free carrier tail. It is concluded that EB-I and EB-II exist in “tight coil” and “expanded coil” molecular conformations respectively which do not change on doping in aqueous HCl.

The use of semi-empirical quantum chemistry to calculate the exciton binding energy of conjugated polymers is discussed. Both the Pariser-Parr-Pople (PPP) model with Ohno parameterization and the models present in the MOPAC program overestimate the exciton binding energy relative to that observed in solid-state materials. Inclusion of Coulomb screening from adjacent chains may correct this overestimation. The solvation energy of a point charge in polyacetylene is calculated as 0.9eV, using Hartree-Fock theory to describe the polarization induced in the solvent chains. It is argued that including screening by modifying the electron-electron interaction energy of the PPP model introduces physically unreasonable side effects and is not consistent with the 0.9eV solvation energy of a point charge. Electron-hole screening models are then discussed along with the need to consider the relative time scales of the electron-hole motion and the dielectric response.

We have studied optical properties of oriented crystalline oligothiophene (T4-T6) thin films to analyze the correlation between optical properties and microstructures in organic films. By using conventional vacuum deposition and organic molecular beam deposition techniques, we fabricated oriented crystalline oligothiophene thin films on fused silica glasses. Luminescence spectrum and dynamic. depend on the thickness of the crystalline films. X-ray and scanning electron microscope analyses show that with an increase of film thickness, the average size of microcrystals increases and then saturates to a constant (∼300 nm). The anisotropy of absorption and luminescence spectra show the orientation of molecules in thick films.

Microwave and millimeterwave obscurants based on typical millimeterwave materials do not environmentally degrade with respect to their physical and electrical properties. The use of conductive polymer coated films and fibers with inherent environmental instabilities are being investigated as possible alternatives. Achieving the optimum electrical performance is highly dependent upon the polymer/dopant combination, deposition conditions, morphology, and volume of the coating that is used. Several conductive polymer coated fiber systems were investigated via thermal analysis. The effects of processing conditions on performance and stability were studied.

We have succeeded in preparing a conductive polyaniline (PAn) with improved thermal stability from a chemical oxidative polymerization of aniline by using an oxidant and a novel protonic acid, m-xylylenedisulfonic acid (XDSA). The acid was synthesized from dibromoxylene and characterized by elemental analysis, IR and NMR spectroscopies. The polymer which is doped with XDSA shows a high conductivity of 5 S/cm. The conductivity does not change with annealing at 125°C in air for over 1000 hours. This polymer exhibits good thermal stability, and this stability is attributed to XDSA dopant, which consists of a bi-functional sulfonic group bonded to a polymer chain. By immersing an anodized tantalum pellet into a reactive solution, PAn doped with XDSA film is formed on the dielectric surface. The tantalum capacitor using PAn doped with XDSA as a counter electrode shows the improved characteristics: high apparent capacitance (90%), and small series resistance (<200mΩ at 100kHz). The capacitor demonstrates an excellent thermal stability due to because of the exceptional heat-resistance of PAn doped with XDSA formed in the capacitor.

Polyaniline (PANI) is a semi-rigid polymer which does not melt and has only limited solubility. Protonation to yield electrical conductivity generally renders a polyelectrolyte which is still less processible. Even selection of the dopant to be bulky or “functionalized” does not render PANI-complex to become melt-processible unless additional additives are used. Neste Oy (Finland) in cooperation with Uniax (U.S.A.) has identified several proprietary additives to allow melt-processibility. We show that in this way PANI-complex starts rheologically to behave in many respects like a conventional polymer. For example, in blends of PANI-complex with polypropylene, their viscosity ratio can be used to render either the PANI-complex or PP continuous, completely analogically to the “classical” polymer blends.

Polyhydroxylated fullerenes were utilized as an efficient hyper cross-linking agent in the synthesis of polyurethane networks. The resultant elastomers exhibited greatly enhanced thermal stability in comparison with those of the corresponding linear polyurethane and analogous elastomers, which were cross-linked by 1,1,1- tris(hydroxymethyl)ethane. A synthetic method leading to the preparation of a thin layer of conductive polyaniline/polyurethane IPN at the near surface of a fullerenol- based elastomeric substrate was demonstrated, using aqueous ammonium persulfate as an oxidizing agent in the presence of HCI. This new material exhibits a conductivity of 2.0 S/cm at ambient temperatures with the retention of most bulk properties of the parent elastomer, such as elongation and tensile strength at break.