Microemulsion and Conventional Emulsion Co-polymerizations of p-Methyl Styrene with Methyl Methacrylate

Abstract

Microemulsion (ME) and conventional emulsion (CE) co-polymerization of p-methyl styrene (pMSTY) with methyl methacrylate (MMA) are carried out at 70 • C using n-pentanol (PA) and n-hexanol (HA), respectively, as co-surfactants along with sodium lauryl sulphate (SLS) as surfactant in the reaction media, and potassium persulphate (KPS) as initiator. The co-polymers are characterized by NMR and GPC techniques. The reactivity ratios are evaluated by employing Fineman-Ross (F-R), Kelen-Tüdös (K-T) and Mayo-Lewis integration (M-L-I) methods. The K-T method yields the reactivity ratios 0.68 ± 0.02 (r pMSTY ), 0.40 ± 0.02 (r MMA ), 0.68 ± 0.02 (r pMSTY ) and 0.68 ± 0.02 (r MMA ), respectively, for the ME and CE co-polymerizations of pMSTY and MMA with PA as co-surfactant in the reaction media. The K-T method yields the reactivity ratios 1.09 ± 0.02 (r pMSTY ), 0.37 ± 0.02 (r MMA ) and 0.78 ± 0.02 (r pMSTY ) and 0.54 ± 0.02 (r MMA ), respectively, for the ME and CE co-polymerization of pMSTY and MMA with HA as co-surfactant in the reaction media.  Koninklijke Brill NV, Leiden, 2008

Semicontinuous heterophase copolymerization of styrene and acrylonitrile

“…Research on this topic has been mainly focused on the polymerization of a single monomer, in spite that copolymers offer a wider range of properties and applications 12. Recently, however, microemulsion copolymerization has drawn more attention 14–28. Microemulsion copolymerization is a much more complex heterogeneous process than its homopolymerization counterpart because the kinetic and colloidal parameters are controlled by the monomers' reactivities and partitioning between the phases 14, 22, 26…”

“…An important drawback of microemulsion polymerization of a single or more monomers is the large amount of surfactant typically used and the low yield of polymer produced, which has hindered its scaling up to industrial level. Methods to increase the polymer/surfactant weight ratio (P/S) have been forwarded recently; basically, most of these methods consist in adding more monomer (semicontinuously, dropwise, in multiple addition or continuously) over a reacting microemulsion or to the final latex obtained in batch homopolymerization2, 32–35 or batch copolymerization 24, 25, 27. Sosa et al32 obtained a latex containing 30 wt % of poly(vinyl acetate) nanoparticles with less than 1 wt % surfactant.…”