Super nucleation and orientation of poly (butylene terephthalate) crystals in nanocomposites containing highly reduced graphene oxide

TL;DR

This study demonstrates that highly reduced graphene oxide acts as a super nucleating agent, significantly enhancing the crystallization and orientation of poly(butylene terephthalate) in nanocomposites, leading to improved interfacial properties.

Contribution

It reveals the super nucleating effect of highly reduced graphene oxide on pCBT crystallization and the resulting crystal orientation and interfacial interactions.

Findings

RGO increases crystallization rate and peak temperature.

Formation of thick α-crystalline lamellae with high melting point.

Strong interfacial interaction between pCBT and RGO nanoflakes.

Abstract

The ring opening polymerization of cyclic butylene terephthalate into poly (butylene terephthalate) (pCBT) in the presence of reduced graphene oxide (RGO) is an effective method for the preparation of polymer nanocomposites. The inclusion of RGO nanoflakes dramatically affects the crystallization of pCBT, shifting crystallization peak temperature to higher temperatures and, overall, increasing the crystallization rate. This was due to a super nucleating effect caused by RGO, which is maximized by highly reduced graphene oxide. Furthermore, combined analyses by differential scanning calorimetry (DSC) experiments and wide angle X-ray diffraction (WAXS) showed the formation of a thick {\alpha}-crystalline form pCBT lamellae with a melting point of ~250 {\deg}C, close to the equilibrium melting temperature of pCBT. WAXS also demonstrated the pair orientation of pCBT crystals with RGO nanoflakes, indicating a strong interfacial interaction between the aromatic rings of pCBT and RGO planes, especially with highly reduced graphene oxide. Such surface self-organization of the polymer onto the RGO nanoflakes may be exploited for the enhancement of interfacial properties in their polymer nanocomposites.