Diblock carbon nanotubes compatibilized immiscible polymer blends

Abstract

Plastic pollution is one of the most serious environmental challenges the world is currently facing. From contaminating soil and oceans to harming animals that consume it, the damages caused by mismanaged plastic waste require immediate action. Of the solutions that currently exist to deal with plastic pollution, the best is recycling. However, the wide variety of plastics available, their immiscibility and the necessity to sort them, makes recycling an expensive process. To solve the problem, interfacial agents are used to improve the miscibility between different plastics. The present dissertation summarizes experiments conducted to evaluate the suitability of carbon nanotubes as compatibilizers for immiscible polymer blends. Nanotubes with dual chemistry (i.e diblock CNTs) allowing them to be compatible with two different polymers have previously been synthesized. Asymmetric double cantilever beam (ADCB) studies were conducted to quantitatively measure the ability of the diblock CNTs to compatibilize polystyrene/poly(methyl methacrylate) PS/PMMA blends. TEM analysis shows the diblock CNTs at the interface between the two polymers. The fracture mechanism taking place suggests that the carbon nanotubes have higher affinity to PMMA than PS. The maximum interfacial fracture toughness of 30 J/m2 obtained was similar to that of block copolymer reinforced interfaces; however, SEM studies of the fractured surfaces also show agglomerates of carbon nanotubes present which may be limiting the efficacy of carbon nanotubes at toughening the interface. Results from varying the annealing time of ADCB samples show that diblock CNTs can also slow down the degradation of polymers at a given temperature