Nanocomposites of epoxy with one-dimensional fibrous poly(ε-caprolactam) nanocrystals via crystallization-driven self-assembly

Abstract

In this contribution, we reported the preparation of nanocomposites of epoxy with one-dimensional (1D) poly(ε-caprolactam) (PA6) nanocrystals via crystallization-driven self-assembly. First, a novel diblock copolymer composed of poly(ethylene oxide) and poly(ε-caprolactam) subchains (PEO-b-PA6) was synthesized via the anionic ring-opening polymerization (ROP) of ε-caprolactam. It was found that the PEO-b-PA6 diblocks displayed crystallization-driven self-assembly (CDSA) behavior in the selective solvents (e.g., water); the 1D fibrous nanocrystals of PA6 were obtained via CDSA approach. Such a CDSA behavior was utilized to generate 1D fibrous PA6 nanocrystals into epoxy thermosets. In this case, the epoxy precursors were used as the solvent selective for PEO subchain of the diblock. Notably, the 1D fibrous PA6 nanocrystals were generated in the epoxy precursors via the CDSA approach. Upon curing, the nanocomposites (i.e., the nanostructured thermosets containing PA6 nanocrystals) were successfully obtained. It was found that epoxy thermoset was significantly nanoreinforced by the PA6 nanocrystals. In the meantime, the fracture toughness of the materials was significantly improved with the incorporation of 1D fibrous PA6 nanocrystals.