Graphite oxide as a carbocatalyst for the preparation of fullerene-reinforced polyester and polyamide nanocomposites

Abstract

Graphite oxide (GO) was discovered to catalyze the ring opening polymerization of various cyclic lactones and lactams, such as ε-caprolactone, δ-valerolactone, and ε-caprolactam, to their corresponding polyesters or polyamides. The resulting polymers were obtained in moderate number average molecular weights (4.8–12.8 kDa) and in good to excellent yields (39–100%) at GO loadings ranging from 2.5–20.0 wt%. Using powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM), it was determined that the carbon catalyst was retained and homogeneously dispersed within the polymer product, resulting in the formation of a carbon-filled composite. TEM also revealed that the carbon transitioned from the lamellar morphology found in GO primarily to nanometre-sized, multiwalled fullerenes; no other discrete carbon morphologies were observed. The inclusion of the carbon material in the polyesters was found to improve the mechanical stiffness of the polymers by up to 400%, as compared to the neat homopolymer.