Polymerization of 2-azabicyclo[2,2,1]heptan-3-one and its copolymerization with 2-pyrrolidone

The anionic polymerization of a bridged bicyclic lactam, 2-azabicyclo2,2,1]heptan-3-one (ABHO), was carried out in bulk and in solution under various reaction conditions. In general bulk polymerization of ABHO was superior to solution polymerization in conversion and degree of polymerization. The resulting polymer exhibited good thermal stability at temperatures up to 300°C. The melting point and decomposition temperature of this polyamide, poly(cyclopentane-1,3-diyliminocarbonyl), were about 307 and 335°C, respectively. Copolymerization of ABHO with 2-pyrrolidone was also made at 30°C and a varying weight percentage of ABHO with potassium pyrrolidonate as catalyst and CS₂ as activator. Copolyamides that contained 15 w % of ABHO decomposed at a temperature higher than the melting point by almost 30°C. Thus the thermal stability of copolymers compared with that of nylon-4, was greatly improved. Moisture sorptions of homopolymers and copolymers were always larger than those of other polyamides (nylon 4 and 6) at any relative humidity. Tenacity and elongation at the break of melt-spun fibers obtained from copolyamides that contained 15 w % of ABHO without the drawing and annealing process were 1.25 g/den and 13.1%, respectively.