Ring opening in lactam polymers



Apparent first-order rate constants and activation energies for the alkaline hydrolysis of polyvinylpyrrolidone, polyactam, vinylpyrrolidone-maleic acid copolymer, N-isopropyl-γ-valerolactam, butyrolactam, and pyrrolidone-N-acetic acid were determined in order to study the influence of structure on the stability of the lactam ring. It was found that the behavior toward alkaline hydrolysis of polyvinylpyrrolidone closely resembles that of its low molecular analogue N-isopropyl-γ-valerolactam. It has been shown that a carboxyl function substituted near the lactam ring has a favorable influence on the ease of hydrolysis. Alkyl substitution on the lactam nitrogen, however, makes the lactam more resistant against hydrolysis.