Investigation of ring opening polymerization of octamethylcyclotetrasiloxane by N-anionic nanostructured polyaniline

Nanostructured polyaniline was synthesized through the chemically oxidative polymerization with interfacial method. The interfacial method is a facile chemical route to preparation of high-quality polyaniline nanofibers under ambient conditions using aqueous/organic interfacial polymerization. The nanofibers have nearly uniform diameters. The synthesis is based on the well-known chemical oxidative polymerization of aniline in a strongly acidic environment, with ammonium peroxydisulfate as the oxidant. Instead of using the traditional homogeneous aqueous solution of aniline, acid, and oxidant, the polymerization is performed in an immiscible organic/aqueous biphasic system, to separate the byproducts (inorganic salts, oligomers, etc.) according to their solubility in the organic and aqueous phases. This nanostructured polymer was used to synthesize N-substituted polyaniline by ring opening reaction of octamethylcyclotetrasiloxane (D4). For the synthesis of N-substituted polyaniline with D4 molecules, the emeraldine base polyaniline was reacted with BuLi to produce the N-anionic polyaniline and then deprotonated polyaniline was initiated the ring opening polymerization of octamethylcyclotetrasiloxane to prepare siloxane-substituted polyaniline through N-substitution reaction. In addition, it should be considered that the polymerization degree of polydimethylsiloxane (PDMS) was limited by back biting reaction of polysiloxane s' oxonium. The microstructure and compositions of obtained polymers were characterized by FT-IR, and Differential Scanning Calorimetry (DSC). Dynamic Light Scattering (DLS) was used to estimate average particle size of synthesized polymers. Also, investigation of thermal behavior of N-substituted polyaniline by thermal gravimetry analysis (TGA) confirmed the results obtained from DSC analysis. The solubility of PDMS-substituted polyaniline in common organic solvents was improved. The conductivity of resulted polymers was investigated by four probe method. The results show that the conductivity of H2SO4-doped polyaniline is 0.03 S.cm-1 and that of N-substituted polyaniline is 0.01 S.cm-1.

کلیدواژه ها:

conducting polymer ، graft polymerization ، polydimethylsiloxane ، chemical modification ، N-substituted polyaniline