In Situ Copolymerization of Lactams for Melt Spinning

The copolymerization of lauryl lactam (LL) with e-caprolactam (e-CL) initiated by the latent, CO2-protected N-heterocyclic carbene-based initiators 1,3-dicyclohexyl-3,4,5,6-tetrahydropyrimidinium carboxylate (6-Cy-CO2), and 1,3-dimethyl-3,4,5,6-tetrahydropyrimidinium carboxylate (6-Me-CO2) has been explored. The temperature-dependent exchange of the protecting group in 6-Cy-CO2 and 6-Me-CO2 with 13C-labeled CO2 is studied to gain knowledge about the onset of CO2 release from the carbene. Under exclusion of moisture, a storable batch containing 75 wt% e-CL, 25 wt% LL, and another 5 wt% 6-Cy-CO2 can be prepared. This batch is successfully used in the in situ melt spinning of poly(e-CL)-co-poly(LL)-based single-filament fibers.