Determination of the cumulative degree of polymerization for the dead‐end polymerization of styrene

Abstract

This article explores the use of a new relation correcting theoretical (DPn) with experimental values obtained in the dead-end polymerization of styrene with azocompound. The syntheses were realized for several starting initiator-to-monomer ratios (C 0 's); values comprised between 10 and 0.1%, and the experimental (DPn) were obtained by size exclusion chromatography. Concerning the theoretical (DPn), a new relation is proposed considering the loss of initiating radicals [I ⅐ ] used in primary termination and both stationary states of I ⅐ and M ⅐ (macromolecular radicals) introduced as Bamford. Finally, (DPn) cum , previously defined by us, is introduced to consider the monomer conversion during oligomerization. Our relation fit very well in a large range of C 0 's, contrary to the application of the usual Mayo rule, and a discussion of validity is proposed. Our model also allows the prediction of (DPn) cum in a large range of telechelic oligomers from 10 to 150.

Kinetic study of the free‐radical polymerization of vinyl acetate in the presence of deuterated chloroform by 1H‐NMR spectroscopy

“…The method for the calculation of (DP n ) cum consists of a divided conversion of the reaction into several intervals i (where i is an integer number) equal to b ( b is a constant), with the assumption that in each interval ( i − 1) b to ib , the reaction is isomolecular 40. The (DP n ) cum value is then given by the various (DP n ) i values of each interval according to eq.…”

Synthesis of fluorinated oligomers for supercritical carbon dioxide applications

“…Polymerization reactions of monomers such as MMA and acrylamide end by termination by a disproportionation mechanism, and the consequent materials are mainly composed of diblock structures, rather than triblocks. However, the utilization of high initiator concentrations can direct reactions toward termination by a combination mechanism 26–30. Boutevin et al29 successfully showed that the utilization of high initiator concentrations leads to termination by combination even for polymerizations of monomers that do terminate by a disproportionation mechanism under ordinary conditions.…”