Solid-phase synthesis of polyamide-6

Abstract

Solid-phase synthesis of PA-6, simultaneously discovered with the reaction of conversion of CL into a polymer and of practical interest primarily as a method for obtaining a polymer constructed of strictly linear macromolecules and containing a minimum amount of CL and especially cyclic oligomers, is not solid-phase in the generally understood meaning of this term. This essentially concerns a set of liquid-phase reactions which differ from ordinary reactions due to the fact that some of the participants and primarily the solvent “molecules,” which the kinetic segments of transfer chains act as, are free of translational mobility, and the entire reaction volume is in a stressed state due to differences in the coefficients of thermal expansion of amorphous and crystalline microregions of the polymer and the developed process of additional crystallization. The presence of an important reaction volume which persists in a relatively wide temperature range and the very large amplitudes of vibrations of translationally immobile reactive groups makes the process kinetically more advantageous than solid-phase polycondensation of monomeric e-aminocaproic acid.