NMR study of poly(urethane acrylates) prepared in the presence of epsilon-caprolactam

Poly(urethane acrylate) samples prepared by the free-radical polymerization of acrylic acid in the presence of epsilon -caprolactam and a linear poly( urethane) were studied by NMR relaxometry, high-resolution NMR spectroscopy , and differential thermal analysis. It was shown that the concentration of poly(urethane) defines the phase composition of the mixture and the chain structure of poly(urethane acrylates), with the first parameter changing fr om single-phase poly(urethane acrylate) to two-phase poly(second phase-acry lurethane caproamide), as the content of the polymer in the starting mixtur e grows. The observed behavior is explained by the decomposition of the car boxyl-containing groups of poly(urethane) under the conditions of the exoth ermic synthesis of poly(acrylic acid) in the complexed state.