Oxidative chemical copolymerization of pyrrole(Py) and aniline (An) by copper perchlorate in acetonitrile was carried out. By varying the monomer feed ratios, the copolymer compositions could be effectively modified. The high-resolution X-ray photoelectron spectroscopy (XPS) analysis using monochromatized Al Kα X-ray source enabled the quantification of the proportions of pyrrole and aniline units in the copolymers. The copolymer composition and microstructure obtained were also characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and electrical conductivity measurements. The results of XPS, FTIR, SEM and conductivity measurements supported the presence of copolymers consisting of random segments of aniline and pyrrole units. The copolymers generally exhibited reduced electrical conductivity, compared to those of the respective homopolymers, probably as a result of the interruption of the polaron lattice by the presence of the second monomer.

A simple technique for the lamination of a conductive polymer film to an inert dielectric polymer film was demonstrated. The electrochemically synthesized and p-toluenesulfonic acid-doped polypyrrole (PPY) film was laminated simultaneously to the argon plasma-pretreated PTFE film during the thermally induced graft copolymerization of the PTFE surface with a functional monomer. The graft copolymerization was carried out using glycidyl methacrylate (GMA) monomer containing 20% v/v hexamethyldiamine (HMDA) and in the absence of any polymerization initiator. Thermally induced graft copolymerization of the GMA monomer on the PPY surface was minimal. The lap shear and T-peel adhesion strengths of the laminates were found to be dependent on the GMA graft concentration on the PTFE surface, which, in turn, was affected by the plasma pretreatment time of the film. To increase the GMA graft concentration for the enhancement of adhesion strength, the plasma-pretreated PTFE surfaces were premodified via UV-induced graft copolymerization with GMA prior to the simultaneous thermal graft copolymerization and lamination process. The modified surfaces and interfaces were characterized by X-ray photoelectron spectroscopy (XPS). Through XPS measurements of the delaminated surfaces, it was found that the PPY/PTFE laminates failed predominantly by cohesive failure inside the PTFE substrate. (C) 2001 John Wiley & Sons, Inc.

A novel process for the metallization of polypyrrole (PPY) film surface through consecutive electroless plating of palladium and copper in the complete absence of the SnCl2 sensitization step was demonstrated. X-ray photoelectron spectroscopy (XPS) technique was used to characterize the polymer surface at each stage of the metallization process. It was found that only the fully reduced PPY film could reduce palladium ions to palladium metal (Pd(0)) in substantial amounts from either the Pd(NO3)2 or PdCl2 acid solution. The palladium metal was necessary for catalyzing the subsequent electroless plating of copper. The reduction of Pd(II) ions in acid solution to Pd(0) on the film surface was accompanied by a simultaneous increase in intrinsic oxidation state and doping level of the film. The copper plating process after the palladium uptake step was highly dependent on the [Pd]/[N] ratio on the film. Through XPS and Auger photoeletron spectroscopy measurements, it was postulated that during the electroless copper plating process, the Cu(II) ions were first reduced to Cu(I) on the PPY film surface before complete reduction to copper metal.

Modification of polypyrrole (PPY) films in the salt and deprotonated forms was carried out via UV-induced surface graft copolymerization with methoxy-poly(ethylene glycol) monomethacrylate (PEGMA) macromonomer. Contact angle and X-ray photoelectron spectroscopy (XPS) measurements were used to characterize the surface-modified PPY films. The biocompatibility of the PEGMA polymer-modified films was compared to that of the pristine films based on their ability to reduce protein adsorption, platelet adhesion and blood coagulation (antithrombogenicity property). The studies performed showed that the graft-modified films exhibited excellent biocompatibility based on all three criteria.

The physicochemical interactions of thermally evaporated magnesium atoms with the chemically synthesized polypyrrole film in its salt and partially undoped (deprotonated) forms were studied in situ by x-ray photoelectron spectroscopy (XPS). The changes in the N(Is), Mg(2p), and S(2p) core-level spectra of the films, as well as the changes in the interfacial chemical compositions, were carefully monitored. It was observed that both types of films underwent an increase in intrinsic oxidation state ([=N-]/[-NH-] ratio) in response to the metal deposition process.. Careful analysis of the Mg(2p) and S(2p) spectra revealed that the incoming magnesium atoms reacted with the dopant to form a salt. The observed increase in the intrinsic oxidation state of the films could therefore be attributed to the undoping (deprotonation) process. The interactions had also involved oxygen since a surge in oxygen concentration at the metal/polymer interface was observed with increasing magnesium coverage. From the results obtained, it could be concluded that the interfacial layer consisted of magnesium-dopant salts, magnesium oxides, magnesium cluster, and magnesium metal. (C) 2001 American Vacuum Society.

An in-situ X-ray photoelectron spectroscopy (XPS) study of the physicochemical interactions between deposited copper atoms and chemically synthesized polypyrrole (PPY) films in its salt and partially undoped (deprotonated) forms was carried out. The XPS N(1s) spectra revealed that the incoming copper atoms reacted with the dopant anions in both types of films. This interaction brought about a simultaneous increase in the intrinsic oxidation state (measured by the [=N-]/[-NH-] ratio), of the polymer and is similar to undoping by deprotonation. The above postulation was: further supported by the corresponding changes in the Cu(2p(3/2)) and S(2p) spectra.. Due to the reaction between the copper atoms and the dopant anions of the polymer film, diffusion of copper atoms-into the bulk of the films was limited. The expected diffusion of oxygen from the conjugated polymer bulk, generally perceived as an oxygen reservoir, to the metal/ polymer interface was not observed in the present system. Hence, any interactions between the metal atoms and the polymer were unlikely to have involved oxygen.

X-ray photoelectron spectroscopy was employed for the in situ study of the interactions between thermally deposited aluminium and the chemically synthesized polypyrrole film in its salt and partially undoped/deprotonated forms. Changes in the N(1s), S(2p) and Al(2p) core-level signals, as well as changes in surface elemental stoichiometries, were carefully monitored. It was found that the incoming aluminium atoms reacted initially with the dopant molecules of the film to form a salt. The undoping process was accompanied by an increase in the intrinsic oxidation state ([N–]/[–NH–] ratio) of the polymer to that generally observed in the completely undoped or 25% deprotonated polymer. The intrinsic oxidation state, however, started to fall at high aluminium loading. Furthermore, the migration of bulk adsorbed oxygen to the surface in response to the Al deposition process resulted in an increase in oxygen concentration at the metal/polymer interface. The formation of the N-π-AlOz complex disrupted the π-electron conjugation in the imine units and reduced the imine site to a state equivalent to that of the amine structure, causing the observed decrease in the intrinsic oxidation state of the polymer.