Conducting polyaniline-coated nano silica by in situ chemical oxidative grafting polymerization

Polyaniline (PAni) grafted nano silica were synthesized successfully by in situ polymerization of aniline (An) using ammonium persulphate (APS) as oxidant by three procedures: Firstly, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane (EPTMS) reacted with nano silica. Secondly, the EPTMS modified nano silica reacted with An as an initiator site introduced onto the silica surface, and finally PAni grafted silica was obtained by in situ chemical oxidative An. The chemical grafting of PAni was confirmed by FTIR and UV-Vis. The percentages of grafting EPTMS and An onto nano silica were 24.5 wt% and 10.3 wt%, respectively, calculated from elemental analysis (EA), while the percentage of grafting PAni was 157.7wt% as a mass ratio of the grafting PAni and charged nano silica, investigated by TGA. In addition, characteristic agglomerate morphology of PAni was observed in the composite by SEM. The electrical conductivity of the product was 2.6 x 10(-6) S cm(-1) and it manifested that the resulted product was a typical semiconductor. Copyright (C) 2007 John Wiley & Sons, Ltd.