Emulsion copolymerization of butyl acrylate and glycidyl methacrylate: Determination of monomer reactivity ratios

Copolymers of butyl acrylate (BA) and glycidyl methacrylate (GMA) were prepared by batch emulsion copolymerization at 75°C, using potassium persulphate (KPS) as an initiator, sodium dodecylbenzene sulphonate (SDBS) as an emulsifier and sodium bicarbonate as a buffer. Composition of copolymers was determined by elemental analysis and the monomer reactivity ratios were estimated by five conventional linear methods at low monomer conversions, i.e., methods of Mayo-Lewis (ML), Fineman-Ross (FR), inverted Fineman-Ross (IFR), Ezrielev-Brokhina-Roskin (EBR) and Kelen-Tüdös (KT). All methods resulted in higher reactivity ratios for GMA comparing to those of BA (ML: rB = 0.15 and rG = 1.51, FR: rB = 0.22 and rG = 1.85, IFR: rB = 0.16 and rG = 1.57, EBR: rB = 0.18 and rG = 1.77, and KT: rB = 0.30 and rG = 1.57). The results also showed that, compared to homogeneous polymerizations (bulk and solution), reactivity ratio of GMA is reduced in emulsion polymerization due to its relative water-solubility, whereas the reactivity ratio of BA is distinctly increased. The effect of the reactivity ratios on the monomer conversion was primarily studied, as well. The results showed that monomer conversion is increased when using higher GMA feed content due to higher reactivity of GMA.