Cross-Chain Transfer Rate Constants of Styrene-Terminated Radicals to Methyl Acrylate and Methyl Methacrylate

Abstract

The chain transfer-to-monomer dominated regime of the molar mass distribution of lowconversion emulsion copolymers of styrene and methyl acrylate and of styrene and methyl methacrylate of various compositions, prepared with varying initiator concentrations, was analyzed with size exclusion chromatography. By extrapolation of the values of the slope of the natural logarithm of the number molar mass distribution to zero initiator concentration, it was possible to determine the average chaintransfer coefficient as a function of composition. By calculation of the ratio of the concentrations of styreneterminated radicals and methyl (meth)acrylate-terminated radicals with an appropriate propagation model, the values of the cross-chain transfer rate constants of styrene-terminated radicals to methyl acrylate and methyl methacrylate could be deduced. These values were interpreted in the light of newly gained insights into radical propagation and transfer reactions.

Preparation and characterization of oligomeric terpolymers of styrene, methyl methacrylate and 2-hydroxyethyl methacrylate: A comparison of conventional and catalytic chain transfer

“…In the case of a copolymerization, the kinetic parameters and concentrations should be based on overall radical and monomer concentrations. [6][7][8] Conventional chain transfer agents, such as thiols, have chain transfer constants in the range 10 -2 -10; consequently high concentrations are required to significantly reduce the molecular weight of the polymer. [9] Since thiols are odorous and toxic, any residuals require removal from the polymer product.…”

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

“…[7,8] An alternative formulation, [9] which has been shown to be of equivalent reliability by Heuts and Davis, [10] makes use of the information provided by the complete molecular weight distribution (MWD) (P(M)) to obtain consistent values for chain transfer coefficients. [7,8,[11][12][13][14][15][16] In the portion of this distribution where chain termination is dominated by chain transfer to monomer, the relationship ln(P(M)) / ÀC M Â M/M 0 applies, where M 0 is the molecular weight of the monomer.…”

Determination of Monomer Transfer Constants in Emulsion Polymerization

“…The parameters shown in lines 1 to 4 (from C m to u) are used for the present model CLD function. Note that what is important is not the absolute values of k p [M] p and " t t e , but the ratio of 1/k p [M] p " t t e to C m , as shown in Equation (8). If we neglect the effect of the unknown chains, the slope of the CLD method would be g = 5.05 6 10 -5 .…”

“…If the CLD follows the most probable distribution, the W (log 10 r) curve has the peak at r = P w . The peak location would be r = 2/g for the distribution function given by Equation (8). If we evaluate the slope by the tangent at this location, Equation (13) gives:…”