Surface Polymerization and Precipitation Polymerization of Aniline in the Presence of Sodium Tungstate

Abstract

Conducting polyaniline films are spontaneously produced on surfaces immersed in the aqueous reaction mixture used for the oxidation of aniline. When a small amount of sodium tungstate, 0.5−5 mol % relative to aniline, is added into the medium, the induction period of the reaction becomes several times longer and the precipitation polymerization is delayed. The surface polymerization of aniline, which precedes the precipitation mode, then produces thicker polyaniline films. The morphology of the films changes from granular to coral-like at the same time. The conductivity of the polyaniline is moderately reduced as the concentration of tungstate increases.

Heterophase Synthesis of Humic Acids in Soils by Immobilized Phenol Oxidases

“…10.6). It is important to underline that the concept of surface polymerization implies that polymeric organic films are produced on the surface before polymerization in the solution bulk has started (Sapurina et al 2003). However, further experiments are needed to define the reaction sequence at solid/solution interface leading to humic polymers formation.…”

Assembly of Polyaniline Nanostructures

“…In order to verify our mechanism, sodium tungstate was used to elongate the polymerization induction time. [30,31] When 0.060 mmol/ 10 ml sodium tungstate was added into the aqueous solution, the obtained product is a mixture of particles, nanofibers, and little nanosheets as shown in Figure 2A.…”

Surface Characterization of Absorbing Polymer Films Deposited on Transparent Glasses

“…Previous results [3,4] indicated that two processes dominate in the in situ polymerization of aniline, adsorption (surface) polymerization and precipitation, the latter that occurs in the bulk phase; adsorption by a film growing on a solid substrate is a fast process taking place after a period of induction, which varies according to solutions, substrates, and temperatures used during the synthesis [3]. In our case, we expect that ultra thin PANI films are formed on the substrate surfaces 20 and 25 min after starting the polymerization reaction.…”

“…Recent reports [1][2][3][4][5][6] about how thin films of a conjugated, conducting polymer, polyaniline (PANI), are adherent and conductive when deposited on inorganic particles, textiles and a variety of solid substrates, such as transparent glass and flexible poly(ethylene terephthalate), broadens its applicability on sensors and electronic devices. A common method of preparation of these PANI films is by immersing a solid substrate in the reaction medium containing both monomer and oxidant.…”

“…A common method of preparation of these PANI films is by immersing a solid substrate in the reaction medium containing both monomer and oxidant. The polymerization initiates by adsorption of oligomers on the substrate surface, followed by nucleation, and growth of a polymer film [3]. This process is called in situ adsorption polymerization since the film thickness (or reaction yield) increases with the reaction time [4][5][6].…”