Polymerization in magnetic field:: XVIII.: Influence of surfactant nature on the synthesis and thermal properties of poly(methyl methacrylate) and poly[(methyl methacrylate)-co-(epoxypropyl methacrylate)]

BACKGROUND: The possibility to use beta-cyclodextrin as biodegradable tensioactive and an electromagnetic field in order to improve the kinetic parameters of radical emulsion polymerization is of interest. Thus, the influence of different surfactants - sodium lauryl sulfate (SLS) and beta-cyclodextrin (CD) - on the pathway of emulsion polymerization of methyl methacrylate (MMA) and emulsion copolymerization of MMA with 2,3-epoxypropyl methacrylate (GMA) performed with or without the presence of a continuous electromagnetic field (MF) was studied. RESULTS: The presence of the MF leads to a considerable increase of the conversion during the first part of the reaction if the classic surfactant (SLS) is used. The reactions perfomed without MF and with CD exhibit a decrease of the conversion and of the polymerization rate as compared with the variants using SLS. The swelling rate and the maximum degree of swelling vary with the surfactant nature and with the reaction conditions and MF presence. Data from thermogravimetry and differential scanning calorimetry evidence the dependences between the polymer characteristics and the preparation conditions. CONCLUSION: This research underlines the coupling possibilities of the influence of a MF - growth of the reaction rate and conversion explained through radical pairs mechanism - with a combination of the 'cage' effect and 'conformational control' afforded by CD. The presence of MF and CD during the syntheses leads to an increase of T, and an increase of PMMA and P(MMA-co-GMA) thermal stability. (C) 2007 Society of Chemical Industry.