Functionalization of MWCNTs with silver nanoparticles decorated polypyrrole and their application in antistatic and thermal conductive epoxy matrix nanocomposite

Abstract

A facile approach for fabricating antistatic and thermally conductive epoxy matrix nanocomposites has been carried out by mixing terephthalic acid-doped MWCNTs with a silver nanoparticle decorated polypyrrole functional coating (MWCNTs@Ag-PPy@COOH). MWCNTs@Ag-PPy@COOH was synthesized via the following steps. Carboxyl groups were first generated on the surface of MWCNTs (MWCNTs–COOH) after mixed acid treatment. Then, pyrrole was grafted onto MWCNTs–COOH (MWCNTs-Py) by the reaction of carboxyl and amine. Furthermore, pyrrole was polymerized on the surface of MWCNTs (MWCNTs@Ag-PPy) initiated by AgNO₃, and silver nanoparticles were decorated onto PPy at the same time. Lastly, terephthalic acid was doped in the repeat unit of PPy through the coordination of carboxyl and pyrrole. Chemical structures of MWCNTs@Ag-PPy@COOH were characterized by FTIR, EDS, XPS, Raman, TGA, SEM and TEM. Results indicated that Ag decorated PPy was successfully covalently bonded onto the surface of MWCNTs, which enhanced the conductive and heat-conducting capabilities. More importantly, because –COOH groups participated in the curing reaction, the dispersion of MWCNTs@Ag-PPy in epoxy matrix was improved after doping terephthalic acid in the repeat unit of PPy. As a result, antistatic and thermally conductive properties were well acquired. The percolation surface resistivity was decreased to 1.3 × 10⁸ Ω sq⁻¹ at 0.5 wt% concentration and thermal conductivity was increased by more than 170% compared to neat epoxy at 10 wt% concentration of MWCNTs@Ag-PPy@COOH.