Graphene Oxide-Graft-Poly(l-lactide)/Poly(l-lactide) Nanocomposites: Mechanical and Thermal Properties

Abstract

Abstract:The surface modification of graphene sheets with polymer chains may greatly hinder its aggregation and improve its phase compatibility with a polymer matrix. In this work, poly(L-lactic acid)-grafted graphene oxide (GO-g-PLLA) was prepared via a simple condensation polymerization method, realizing its dispersion well in organic solvents, which demonstrated that the surface of GO changed from hydrophilic to hydrophobic. GO-g-PLLA can disperse homogeneously in the PLLA matrix, and the tensile test showed that the mechanical properties of GO-g-PLLA/PLLA were much better than that of GO/PLLA; compared with GO, only 3% GO-g-PLLA content can realize a 37.8% increase in the tensile strength for their PLLA composites. Furthermore, the differential scanning calorimetry (DSC) and polarized optical microscopy (POM) results demonstrated that GO-g-PLLA shows a nucleating agent effect and can promote the crystallization of PLLA.

Preparation and characterization of phosphorylated graphene oxide grafted with poly(L‐lactide) and its effect on the crystallization, rheological behavior, and performance of poly (lactic acid)

“…The content of C─OH on PGO greatly reduced due to its consumption of initiating open‐ring polymerization. As shown in the Table , the C/O ratio of PGO was 2.03, while the C/O ratio of PGO‐PLLA was 1.32, which is much lower than that of PGO, indicating the increase of oxygen content, and this change was due to the higher content of oxygen in PLLA chains . Therefore, this study fully proved that PGO is successfully grafted with the PLLA chains.…”

“…As shown in the Table 1, the C/O ratio of PGO was 2.03, while the C/O ratio of PGO-PLLA was 1.32, which is much lower than that of PGO, indicating the increase of oxygen content, and this change was due to the higher content of oxygen in PLLA chains. 38 Therefore, this study fully proved that PGO is successfully between the graphene sheets. In order to maintain the stability of two-dimensional crystal structure and reduce the surface energy, the surface and edges of PGO are easy to bend and wrinkle.…”

“…The asymmetric stretching vibration of hydroxyl group at 3402 cm ‐1 in the band was strengthened, which proved that the PGO was successfully prepared. In the PGO‐PLLA band, the asymmetric stretching vibration peak of hydroxyl group at 3402 cm ‐1 basically disappeared, and the strengthening of carbonyl stretching vibration peak at 1743 cm ‐1 indicated that esterification reaction occurs, which confirmed that the PLA molecules synthesized by lactide ring‐opening had been grafted onto the PGO surface successfully . The infrared absorption peak at 1758 cm ‐1 was the characteristic C═O absorption peak of PLA0.…”

“…In the PGO-PLLA band, the asymmetric stretching vibration peak of hydroxyl group at 3402 cm -1 basically disappeared, and the strengthening of carbonyl stretching vibration peak at 1743 cm -1 indicated that esterification reaction occurs, which confirmed that the PLA molecules synthesized by lactide ring-opening had been grafted onto the PGO surface successfully. 38 The infrared absorption peak at 1758 cm -1 was the characteristic C═O absorption peak of PLA0. When 0.3 wt% PGO-PPD was introduced into matrix PLA, the C═O characteristic absorption band of PLA2 samples was shifted to lower wavenumbers of 1755 cm −1 .…”

Recent Progress in Graphene/Polymer Nanocomposites

“…[ 64,65 ] Moreover, the graphene functionalization (covalent and noncovalent) could give rise to strong interfacial interaction. [ 66,67 ] The interface bridges the reinforcement and matrix, which transfers the stress from matrix to reinforcement. [ 68 ] In general, the intrinsic interfacial interaction between graphene and polymer is the weak van der Waals force, which easily results in the interface debonding under loading thus causes the failure.…”