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Liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) in the positive and negative ion modes was used for the characterization of a block copolymer consisting of methoxy poly(ethylene oxide) (mPEO), an epsilon-caprolactone (CL) segment and linoleic acid (LA), used as surfactant in water-based latex paints. Chromatographic separation was obtained based on the number of CL units in the polymer species and the presence of an mPEO and/or LA tail. Different ionization methods were found to be complementary and only their combination allowed the qualitative profiling of the chemical composition. The LC/MS method has proven valuable for following the reaction in time, as well as for comparison of different polymeric surfactants.

A redox initiating system, consisting of t-butyl hydroperoxide (tBHPO), isoascorbic acid (iAA), and ethylenediaminetetraacetic acid ferric-sodium salt (FeEDTA) was employed in emulsion polymerizations of methyl methacrylate (MMA) at high solids contents of 30 wt % in water. The system was stabilized using, linoleic acid (LA)-functionalized and nonfunctionalized surfactants based on methoxy-PEG (MPEG) and e-caprolactone (CL). To optimize polymerization conditions and to avoid coagulation and solidification during the reaction, the temperature, the amount of initiator, the chemical characteristics of the surfactant, and the surfactant to monomer ratio were varied. MPEO 45 -CL 6.5 -LA (the subscripts refer to the average number of repeating monomer units) was found to be the most suitable surfactant, as it performs adequately under suboptimal reaction conditions. In the emulsion polymerization of MMA in water at $30 wt %, best results were obtained at a reaction temperature of 60 C, with an initiator system comprising tBHPO iAA and FeEDTA, and a surfactant to monomer ratio of 10/90 by weight or higher. Under these conditions, stable PMMA latices with average particle sizes of 200-300 nm were obtained at complete monomer conversion. V V C 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: [4234][4235][4236][4237][4238][4239][4240][4241][4242][4243][4244] 2009