Two methods for the functionalization of single-walled nanotubes were proposed, namely grafting of acyllactam groups or amine-terminated polyimides. Such modification allows for the preparation of stable nonsagging nanotubes dispersions in the melted e-caprolactam. These dispersions were further utilized for in situ ring-opening anionic polymerization of ecaprolactam with e-caprolactam magnesium bromide as a catalyst and N-acetyl-e-caprolactam as an activator. Some unique features of the obtained novel nylon-6/nanotubes composites are significantly increased thermal stability (T 5% up to 400 C), enhanced compression modulus and Izod impact strength of polymer blocks (by 25% and 150%, respectively) and advanced tensile strength and elongation of polymer films. Such an improvement in the properties of the composites in comparison with neat nylon-6 was gained by the addition of as little as 0.1-0.01 wt% of modified nanotubes.

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The anionic polymerization of ε-caprolactam in the presence of single-walled carbon nanotubes with grafted acyllactam groups or polyimide macromolecules is performed. It is shown that the polymerization of ε-caprolactam slows down with an increase in the filler concentration. The introduction of 0.01 wt % nanotubes with polyimide fragments into polycaproamide leads to a 25% increase in the compressive modulus. In this case, the Izod impact strength is 10 kJ/m 2 , that is, 150% higher than that for an unfilled polycaproamide or polycaproamide containing other types of nanotubes.