Toughness Enhancement in Polyactide Nanocomposites with Swallow-Tailed Graphene Oxide

Graphene oxide modified with long flexible hydrocarbon chains attracts increasing interest in toughing and stabilizing polymer nanocomposites. Herein, graphene oxide bearing with two types of long alkyl chains, namely 2-octyldodecylamine (swallow tail) and dodecylamine (linear), were prepared and introduced into polylactide by a master batch melt blending process. Swallow-tailed graphene oxide sheets show a homogeneous and stable dispersion in organic solvents, suggesting that the bulky groups enable to weaken Van der Waals forces, which is in consistence with the increment of 4.4 Å in interlayer spacings. Moreover, 2-octyldodecylamine-functionalized graphene oxide sheets allow polyactide to be highly toughness without sacrificing tensile strength. In comparison to neat polylactide, the polylactide nanocomposites with 0.3 wt % 2-octyldodecylamine-functionalized graphene oxide display about 400% increase in the elongation at break. The crystallization properties of polylactide were also improved with nanofillers. In addition, the polylactide nanocomposites exhibit high thermal stability in the presence of 0.3 wt % swallow-tailed graphene oxide sheets. Therefore, this study provides a new concept to modify graphene oxide to elevate the dispersion of graphene oxide, which contributes to enhancing interfacial interaction and consequently endowing polymer nanocomposites with high toughness and high stability.