Emulsion copolymerizations of methyl acrylate with methyl methacrylate and with acrylonitrile

Emulsion copolymerizations of methyl acrylate (MA) with methyl methacrylate (MMA) and with acrylonitrile (AN) were carried out employing sodium lauryl sulphate (SLS) as a surfactant, potassium persulphate (KPS) as an initiator, and water as a dispersion medium at 70degreesC. The copolymers were characterized by FTIR, NMR, and TG/DTA techniques. Another series of emulsion copolymerization experiments were carried out employing HYOXYD X400 as a co-surfactant, along with SLS, and keeping all the other experimental conditions the same. The reactivity ratios of these monomer pairs were evaluated by employing the graphical procedures by Fineman-Ross (F-R) and Kelen-Tudos (K-T). The K-T method yielded the reactivity ratios 0.95 +/- 0.05 (r(MA)) and 2.05 +/- 0.05 (r(MMA)), for the monomer pair MA/MMA, and 1.84 +/- 0.05 (rMA) and 0.98 +/- 0.05 (r(AN)) for the monomer pair MA/AN. When HYOXYD X400 was employed as a co-surfactant in the emulsion copolymerization experiments, the reactivity ratios were 0.75 +/- 0.05 (r(MA)) and 2.17 +/- 0.05 (r(MMA)) for the monomer pair MA/MMA, and 1.23 +/- 0.05 (r(MA)) and 0.89 +/- 0.05 (r(AN)) for the monomer pair MA/AN. These reactivity ratios obtained for the monomer pairs MA/MMA and MA/AN deviate from the values obtained by bulk and solution copolymerization methods reported in the literature.