Synthesis of a Water Dispersible Inter-Polymer Complex of Polyaniline
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Figure 1: Polyaniline undergoes a pH induced conductor-to-insulator transition. There has been tremendous effort to render polyaniline soluble or dispersible in common solvents while stabilizing it against pH induced conductor-to-insulator
transition2 . Our group approached this problem by synthesizing polymeric between polyaniline and a polyelectrolyte3 . This method renders polyaniline dispersible in water as well as stabilizes the conductive from to pH 8. These make the polymeric complex of polyaniline a more desirable material applications4 .
complexes soluble or properties for many
INTER-POLYMER COMPLEXES OF POLYANILINE The water-dispersible polyaniline of the present study is an inter-molecular complex of polyaniline and poly (acrylic acid) (PAA). This polymeric complex, PAN:PAA, belongs to the family of double-strand conducting polymers. There are two components of the complex: Strand 1 is a conducting polymer such as polyaniline, PAN. Strand 2 is a polyanion that also serves as a polymeric dopant for PAN. The two polymer strands are bonded non-covalently by electrostatic, hydrogen bonding and van der Waals forces. The ideal structure of the complex is that of two strands bonded in a side-by-side fashion. The actual structure is likely to be less ordered. Previous characterization of polymeric complex provides certain evidence for a side-by-side orientation of the two polymer strands5 . When a specific procedure for template guided synthesis is followed, the properties of the product are consistent with that of a double-strand complex. One of the useful properties of the inter-polymer complex is that it renders polyaniline soluble or dispersible in water. This property is especially useful for processing thin films for optical and electronic applications, or for coatings of anticorrosion paints. The property of solubility or dispersibility is derived from the fact that the second strand contains anionic functional groups or polar groups to enhance solvation by water. Being a complex between a polycation (PAN) and the polyanion (PAA) does not automatically guaranty water dispersibility. In fact, most of the polycation:polyanion complexes in the literature are insoluble hydrogels. In the case of PAN:PAA complex, there is a significant driving force for aggregation due to the fact that PAN molecules are easily aggregated. We found that the reaction conditions and the reagent concentrations influence whether a reaction product is suspendable in water or a precipitate. In this study, we will examine the effect of varying the total reaction concentration on the dispersiblity of the reaction products. TEMPLATE-GUIDED SYNTHESIS: SYNTHETIC APPROACH In general, a template-guided synthesis is carried out in a series of steps. First, the template and the monomer are assembled into an adduct, then the acidity of the adduct solution is adjusted, and finally the polymerization is anitiated. It is important to note that the steps must be carried out in the p
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