Colloidal Polyaniline Research Articles

Synthesis of novel polyaniline colloids using chemically grafted poly( N-vinylpyrrolidone)-based stabilizers

We report the synthesis of polyaniline colloids using a new polymeric steric stabilizer based on a poly( N-vinylpyrrolidone) copolymer. This copolymer stabilizer contains pendant aniline groups which are believed to participate in the in situ aniline polymerization, leading to the chemical grafting of the stabilizer onto the surface of the polyaniline particles. The stabilizer is compatible with both (NH 4) 2S 2O 8 and KIO 3 oxidants and so represents an improvement over our earlier work. Our electron microscopy studies have confirmed that the polyaniline colloid morphology depends on the oxidant used for the aniline polymerization. Thus the (NH 4) 2S 2O 8 oxidant produces spherical particles while the KIO 3 leads to the formation of “rice-grain”-shaped particles. The mass ratio of grafted stabilizer/polyaniline has been indirectly determined by assaying postreaction supernatant solutions by colorimetry using congo red dye as a complexing agent. The polyaniline colloids were further characterized by a wide range of techniques including FTIR and visible absorption spectroscopy, microanalysis, dc conductivity, and thermogravimetric analysis.

Preparation and characterisation of polyaniline colloids using a monodisperse poly(ethylene oxide)-based steric stabiliser

The synthesis of polyaniline colloids using a new polymeric steric stabiliser of narrow molecular weight distribution based on poly(ethylene oxide) is reported. This model stabiliser contains one tertiary amine group per polymer chain which is believed to participate in the in situ aniline polymerisation, leading to the chemical grafting of the stabiliser onto the surface of the polyaniline particles.These polyaniline colloids were characterised by a wide range of techniques including electron microscopy, FTIR and visible absorption spectroscopy, microanalysis, d. c. conductivity and thermogravimetric analysis. The colloids possess a polydisperse non-spherical morphology and remarkably high solid-state electrical conductivity (0.1–1.0 S cm–1), despite the presence of the electrically insulating grafted stabiliser. The mass ratio of grafted stabiliser : polyaniline was determined indirectly by 1H NMR spectroscopy analysis of the post-reaction supernatant solutions. In addition, flocculation experiments were carried out to assess the aggregation stability of these dispersions in the presence of added electrolyte.

Novel colloidal polyaniline–silica composites

We have prepared novel colloidal polyaniline–silica composites by chemically polymerising aniline in the presence of small silica particles of 38 ± 7 nm diameter; these composites have been characterised by various techniques including thermogravimetry micoanalyses, scaning, electron microscopy, photon correlation spectroscopy, visible absorption and FTIR spectroscopy and conductivity measurements.

Poly(1-vinylimidazole- co-4-aminostyrene): steric stabilizer for polyaniline colloids

We report the preparation and characterization of polyaniline colloids using a new steric stabilizer based on poly(1-vinylimidazole). This stabilizer contains pendant aniline units which participate in the aniline polymerization, resulting in the formation of sterically stabilized polyaniline particles which have a non-spherical ‘rice-grain’ morphology. It is shown that this form of polyaniline is more processable than the bulk powder that is normally obtained from a conventional chemical synthesis. The solid-state conductivity of solution-cast films or compressed pellets of these dispersions is reasonably high (∼1 × 10 −2 S cm −1), despite the presence of the insulating outer layer of chemically grafted stabilizer. We have characterized these polyaniline colloids using various techniques including electron microscopy, cyclic voltammetry, visible absorption and Fourier transform infra-red spectroscopy.

Novel colloidal polyaniline fibrils made by template guided chemical polymerization

The colloidal fibrils of polyaniline–poly(acrylic acid) complex were first synthesized by template guided chemical polymerization; their morphology and the electronic absorption spectra in aqueous solution are reported.

Aqueous colloidal dispersions of polyaniline formed by using poly(vinylpyridine)-based steric stabilizers

Colloidal polyaniline has been prepared in acidic aqueous media by chemical grafting of polyaniline onto a tailor-made polymeric surfactant. The surfactant, which acts as a steric stabilizer, used in this study is the random copolymer poly(2-vinylpyridine-co-p-aminostyrene). This surfactant contains pendant aniline units which participate in the aniline polymerization, resulting in the formation of sterically stabilized polyaniline particles which have a nonspherical «rice grain» morphology

Synthesis and Characterization of Aqueous Colloidal Dispersions of Poly(Vinyl Alcohol)/Polyaniline Particles

Abstract Colloidal polyaniline has been prepared in acidic aqueous media by a modified chemical polymerization of aniline in the presence of a tailor-made polymeric surfactant. The surfactant which acts as a steric stabilizer used in this study is derivatized poly(vinyl alcohol-co-vinyl acetate). This surfactant contains pendant aniline units which participate in the aniline polymerization, resulting in the formation of sterically-stabilized polyaniline particles which have a non-spherical “rice-grain” morphology. It is shown that this novel form of polyaniline is more processable than the bulk powder that is normally obtained from a conventional chemical synthesis. The solid-state conductivity of solution-cast films or compressed pellets of these dispersions is surprisingly high (≃1 S/cm), despite the presence of the insulating outer layer of chemically-grafted stabilizer. We have characterized these polyaniline colloids by a wide range of techniques including electron microscopy, cyclic voltammetry and ...