Chemical Engineering of the Single-Walled Carbon\nNanotube−Nylon 6 Interface

Abstract

We report an approach to the chemical engineering of the single-walled carbon nanotube\n(SWNT)−polymer interfacial interaction in a nylon 6 graft copolymer composite which is based on the\ndegree of SWNT functionality. Continuous fibers are drawn from composites fabricated from the in situ\npolymerization of caprolactam with SWNTs possessing a range of carboxylic acid (SWNT-COOH) and\namide (SWNT-CONH₂) functionalities. Mechanical performance evaluation of the composite fibers shows\nthat a high concentration of the carboxylic acid functional groups leads to a stronger SWNT−nylon interfacial\ninteraction, as reflected in greater values of the Young's modulus and mechanical strength. Replacement\nof the COOH group by CONH₂ in the SWNT starting material changes the grafting polymerization chemistry,\nthereby leading to the covalent attachment of longer graft copolymer chains to the SWNTs, and alters the\ncomposite morphology while increasing the composite flexibility and toughness.