Emulsion Polymerization of Methyl Methacrylate with Iso-Octyl-3-Mercapto Propionate as Chain Transfer Agent

RONCO, L.I.; MINARI, R.J.; VEGA, J.R.; GUGLIOTTA, L.M.

Bahía Blanca

Simposio; IX Simposio Argentino de Polímeros - SAP 2011; 2011

In this work, the isothermal batch emulsionpolymerization of methyl methacrylate (MMA) with iso-octyl-3-mercaptopropionate (iOMP) as chain transfer agent (CTA) was investigated, with the aim of studying the CTA effect on the kinetics and MWD of the produced poly(methyl methacrylate) [PMMA]. Finally, the experimental results were interpreted in the light of a first principle mathematical model. The results were interpreted with the help of a first principle mathematical model. The iOMP concentration exhibits a significant effect on both the polymerization kinetics and the MWDs. It was observed that the used of iOMP as CTA diminishes the polymerization rate and increases the particles number, as a consequence of: i) the lower reactivity of the iOMP radicals with respect to the monomeric radicals; and ii) the desorption of the iOMP radicals from the polymer particles towards the aqueous phase. These hypotheses allowed an adequate fitting of experimental data with the proposed mathematical model. It was also observed that the MWD of the PMMA was controlled by transfer to the CTA, with a reduction of the average molecular weights along the reaction and an accumulation of iOMP with respect to MMA (i.e., CX i < 1).