Chemical polymerization of aniline in phenylphosphinic acid

The chemical polymerization of aniline was performed in phenylphosphinic acid (APP) medium using ammonium peroxidisulfate as the oxidizing agent, at 0 ºC and 25 ºC. The yield of polyaniline (PANI) was about 60–69 %. The polymerization process required an induction time 8–10 times greater than in other acids (hydrochloric, sulfuric). The average density of the obtained polymer was 1.395 g cm-3 for PANI-salt and 1.203 g cm-3 for PANI-base. The acid capacity of PANI depends on the synthesis parameters and the maximum value was 15.02 meq/g polymer. The inherent viscosity of PANI was 0.662 dl/g at aniline/oxidant molar ratios >2 and 0 ºC. The oxidation state was a function of the synthesis parameters and lay between 0.553–0.625, as determined from UV-VIS and titration with TiCl3 data. The PANI samples were characterized by measurements of their density, inherent viscosity, conductivity, acid capacity, FTIR and UV-VIS spectrum, and thermogravimetric data.