Long-Living Anions Could Dramatically Change the Overall Physical Properties of a Polyamide (Nylon 6) Synthesized by a Novel Process.

We devised a novel strategy of two-stage anionic polymerization of (ε-caprolactam) in a twin screw extruder to control the generation of branched structures. Long-living anions of nylon 6 prepared in the first extrusion gave rise to a change in the molecular structure when they interacted with diamine added during the second extrusion. It has been found that the transfer of living anions between functional molecules having the same anion-forming groups affects the structural change of the resulting polymer molecule. The variation in chain structure has resulted in dramatic changes in the physical and dynamic properties of the polymer despite changes in molecular weight of less than 2 without forming a network structure. Tensile elongation and toughness at the optimum concentration of the additive were increased by 5 and 10 times, respectively, which was enough for the resulting polymer to be classified as a super-tough nylon without a toughener. It can be widely used as a matrix polymer for diverse composite materials.