Kinetics of azo-initiated 1-vinyl-2-pyrrolidone polymerizations at low conversions in aqueous media

Abstract

The free-radical polymerization behavior of 1-vinyl,2-pyrrolidone (NVP) was studied at low conversions, using capillary dilatometry. The aqueous media were kept at neutral pH and the studies were conducted isothermally, at 40 or 45°C. The azo-type initiators used were 4,4Ј-azobis-4-cyanopentanoic acid (ACPA), 2,2Ј-azobisisobutyronitrile (AZBN), and 2,2Ј-azobis[2-(2-imidazolin-2-yl)propane dihydrochloride] (ABDH). The monomer concentration and initiator concentration ranges were 1.17-2.34 mol L Ϫ1 and 1-8 mmol L Ϫ1 , respectively. The rates of polymerization (R p ) and orders of reaction with respect to NVP and the initiator were evaluated and the kinetic equations were found to be R p ϰ [NVP] [ACPA] 1.2 ; R p ϰ [NVP] [AZBN] 1.1 ; and R p ϰ [NVP] 2.2 [ABDH] 1.1 . The polymers obtained were characterized by their viscosity numbers and correlation of the viscosity average molecular weights made with the type and amount of the azo initiator.

Kinetics and Mechanism of Synthesis of Carboxyl-Containing N-Vinyl-2-Pyrrolidone Telehelics for Pharmacological Use

“…The chain termination mechanism, which affects the order of the reaction rate with respect to the initiator in the radical polymerization of N-vinylpyrrolidone, remains a subject of discussion [ 35 ]. The possibility of both traditional bimolecular chain termination, [ 36 ] and first-order chain termination, in terms of the concentration of active centers, which are often associated with the participation of impurities in chain termination [ 27 , 35 , 37 ], has been shown. However, the development of the gel effect at high conversions of N-vinyl-2-pyrrolidone, noted in [ 27 ], rather indicates the realization of bimolecular chain termination.…”

Free radical kinetics ofN-methylN-vinyl acetamide polymerization at low conversions in aqueous media

“…Profiles of decreases in the capillary height with time and examples on the actual course of dilatometric runs are similar to those obtained in an earlier work. 7 An initial dilatometric conversion rate R p is obtainable according to:…”