Graphene oxide reduces the hydrolytic degradation in polyamide-11

Graphene oxide (GO) was incorporated into polyamide-11 (PA11) via in-situ polymerization. The GO-PA11 nano-composite had elevated resistance to hydrolytic degradation. At a loading of 1 mg/g, GO to PA11, the accelerated aging equilibrium molecular weight of GO-PA11 was higher (33 and 34 kg/mol at 100 and 120 °C, respectively) compared to neat PA11 (23 and 24 kg/mol at 100 and 120 °C, respectively). Neat PA11 had hydrolysis rate constants (kH) of 2.8 and 12 ( × 10−2 day−1) when aged at 100 and 120 °C, respectively, and re-polymerization rate constants (kP) of 5.0 and 23 ( × 10−5 day−1), respectively. The higher equilibrium molecular weight for GO-PA11 loaded at 1 mg/g was the result of a decreased kH, 1.8 and 4.5 ( × 10−2 day−1), and an increased kP, 10 and 17 ( × 10−5 day−1) compared with neat PA11 at 100 and 120 °C, respectively. The decreased rate of degradation and resulting 40% increased equilibrium molecular weight of GO-PA11 was attributed to the highly asymmetric planar GO nano-sheets that inhibited the molecular mobility of water and the polymer chain. The crystallinity of the polymer matrix was similarly affected by a reduction in chain mobility during annealing due to the GO nanoparticles' chemistry and highly asymmetric nano-planar sheet structure. [Display omitted] •Graphene oxide reduces extent of hydrolytic degradation in polyamide-11.•Graphene oxide reduces molecular mobility in polyamide-11.•Polyamide's amide hydrogen bonds with the graphene oxide surface.