Chain transfer to monomer and polymer in the radical polymerization of vinyl neo-decanoate

Abstract

Molecular weight distributions of poly(vinyl neo-decanoate) produced by the bulk polymerization of the monomer to low conversions were investigated to obtain values of the rate constants for the chain transfer to monomer (C M ). The value of C M of 7.5 (· 0.6)Ý 10 − 4 was obtained from a logarithmic plot of the number distribution at 5, 25, and 50 o C, which suggests that the activation energy for chain transfer is on the order of 20-25 kJ mol − 1 . These plots were linear between the number and weight-average degrees of polymerization, but not over the whole molecular weight range for which a significant signal was observed in the gel permeation chromatography (GPC) trace. Modeling suggests that the deviations observed at high molecular weights can be explained by branching of the chains through chain transfer to the polymer, with a branching density as low as 10 −5 , without affecting the slope at low values of the number of monomer unit, N. This deviation from the expected distribution of linear chains was used to estimate the branching densities at low conversion.

Measurement of Transfer Coefficients to Monomer for n‐Butyl Methacrylate by Molecular Weight Distributions from Emulsion Polymerization

“…[45] Long-chain branching could lead to an apparent reduction in the termination rate. [46] At 60 and 70 8C where long-chain branching would be expected to be more significant, it does appear that the slope at the peak molecular weight is appreciably greater than that at the high molecular weight tail used. [5] Thus, it is possible that both A and E A for hk tr,M i in BA may be significantly higher than reported here.…”

Modeling of Emulsion Polymerization, Will It Ever be Possible ? Part‐2: Determination of Basic Kinetic Data Over the Last Ten Years

“…Size exclusion chromatography is crucial in obtaining kinetic parameters in radical polymerization, examples are; to extract propagation rate coefficients from SEC traces of polymer obtained in pulsed laser polymerization [6,7] ; to obtain transfer to monomer rate coefficients [8] ; transfer to polymer rate coefficients [9] ; termination rate coefficients [10] and information on many other aspects of the polymerization mechanism.…”