Synthesis and properties of organo-fly ash/polyaniline with core/shell structure based on emulsion polymerization

Organo-fly ash (OFA) was prepared with pretreated fly ash (FA) and hexadecyltrimethyl ammonium bromide (HDTMAB), and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios (2.0 wt%, 5.0 wt%, 10.0 wt%, 15.0 wt% and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier. A polymerization procedure was supposed. The electrical conductivities of the composites were tested by the four-probe technique. The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction, respectively. Morphologies of FA, OFA and the composites were observed by SEM. The element analysis was performed by energy dispersive spectrometry. The thermal stability of the composites was analyzed by TGA. The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA, and the lowest value was 0.62 S/cm. HDTMAB and PAn were just adsorbed on the surface of FA and OFA, respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA. The surface became smoother after organification of FA by using HDTMAB, and its content on FA surfaces was about 26.9 wt%. The core/shell structure of the composite was observed by SEM analysis. The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system, the heat stability of PAn was increased by decreasing 31.8 wt% of weight loss after introducing 20 wt% of OFA.