Simultaneously enhanced tensile strength and fracture toughness of epoxy resins by a poly(ethylene oxide)-block-carboxyl terminated butadiene-acrylonitrile rubber dilock copolymer

A PEG-b-CTBN diblock copolymer was synthesized via the esterification reaction of hydroxy terminated methoxypolyethylene glycols (PEG) in the presence of a carboxyl-terminated butadiene-co-acrylonitrile copolymer (CTBN) with 4-dimethylaminopyridine (DMAP) as the catalyst. Epoxy thermosets were modified via the formation of a nanostructure. The result of transmission electronic microscopy (TEM) shows spherical domains were homogeneously dispersed into the continuous epoxy matrix and the size is nano-scale. It was noted that the glass transition temperatures decreased with an increase in the content of PEG-b-CTBN, which was evidenced by Dynamic Mechanical Analysis (DMA) and a Differential Scanning Calorimeter (DSC). Through mechanical tests, we found the tensile strength and fracture toughness of epoxy resins were simultaneously enhanced by nanostructured PEG-b-CTBN.