Anionic Polymerization of β-Nitrostyrene under the Influence of High Energy Radiation

Abstract

A B S T R A C T 0-Nitrostyrene (PNS) was polymerized in aprotic solvents. The rate of polymerization increased in the series dimethyl sulf oxide = dimethylf ormamide < N-methylpyr rolidone < hexamethylphosphoric triamide (HMPT). From copolymerization experiments with a-methylstyrene and methacrylonitrile, evidence for an ionic mechanism was obtained. Electron scavengers inhibited the polymerization. Thus it was concluded that in dilute solution the initiation comprises the thermalization of electrons which become solvated and react with PNS to form the radical anion .PNS-. Pulse radiolysis experiments were carried out in HMPT. The spectrum of an intermediate (presumably .PNS-) was recorded. By measuring the rates of the formation of *PNS-and of the decay of solvated electrons the rate constant ke-(solv + ONS) = (9 * 3) x 10' liter/mole-sec was determined. At higher monomer concentrations the polymerization was autoinhibited which is probable due to the fact that direct absorption of radiation by the monomer becomes important. 1637

Reaction of β-Nitrostyrene with Diethyl Malonate in the Presence of Bispidines: The Unusual Role of the Organocatalyst

“…Thus, the study of binary mixtures of components of the catalytic reaction allowed us to establish the following processes: (1) the absence of deprotonation of diethyl malonate by N-benzylbispidine 6 and presumably the formation of a supramolecular complex between them; (2) the probable formation of a supramolecular complex between diethyl malonate and β-nitrostyrene; and (3) the formation of products of conjugated addition of bispidines 6 and 10a to C=C-bonds of nitrostyrene with their subsequent oligomerization (Scheme 7). The anionic polymerization of β-nitrostyrene and its derivatives initiated by bases, including amines, has been described [58][59][60][61][62][63][64], as well as under the action of high-energy gamma radiation [65,66]. However, the above studies were mainly aimed at studying the kinetics of the polymerization process and determining the molecular weight characteristics of the resulting polymers.…”