N-vinylimidazole-N-vinyl-2-pyrrolidone copolymers. Part I. Reactivity ratios, solubility and viscosimetric study

Abstract

Copolymers of N-vinylimidazole M with N-vinyl-2-pyrrolidone (VP), (VI-co-VP) were obtained by radical polymerization using alpha,alpha'-azobisisobutyronitrile as initiator. The copolymers were characterized by H-1 NMR and viscosimetric measurements. The monomer reactivity ratios were estimated to be r(1) = 1.00 for VP and r(2) = 0.07 for VI by the Fineman-Ross and Kelen-Tudos linear procedures. These parameters were also estimated using a computer program based on a non-linear minimization algorithm (NLMA) starting from the values of r(1) and r(2) obtained by the linear procedures. All copolymers could be considered as random. The solubility in chloroform, n-butanol and n-propanol depends on the copolymer composition. Water, methanol and ethanol are solvents, irrespective of the copolymer compositions. The viscosimetric behaviour of unfractionated copolymers of one composition was studied in dilute solution in water (pH 2.0 and 6.0) at 0.01 M (NaCl) ionic strength and in methanol. (C) 1998 Society of Chemical Industry