Synthesizing polystyrene/carbon nanotube composites by emulsion polymerization with non-covalent and covalent functionalization

Polymer/carbon nanotube (CNT) composites were synthesized by first attaching functional groups onto CNT to make them reactive. For this purpose, we developed a combined approach of non-covalent and covalent functionalization process. Covalent functionalization was accomplished through refluxing of CNT with mineral acid (HNO₃) and with oleic acid. The FTIR spectra and zeta-potential data confirmed the effectiveness of functionalization and the improved dispersibility of the functionalized CNT. Styrene was used to synthesize polystyrene (PS)/CNT composites in conjunction with emulsion polymerization, a versatile and industrially important method that is seldom reported for composite synthesis. Our PS/CNT composites had high monomer conversion and the measured thermal and mechanical properties showed significant improvements over pure PS even with modest CNT content.