Combining SEC & MALDI for characterization of the continuous phase in dispersion polymerization

摘要

Dispersion copolymerization of styrene (St) with either acrylonitrile (AN) or methyl methacrylate (MMA) in 1-propanol/deionized water medium were carried out using Bisomer S20W (polyethylene oxide macromonomer with a methacrylic end group) as stabilizer. The serums of the St/AN and St/MMA latexes were characterized in terms of molar mass and composition by the combination of Size Exclusion Chromatography (SEC) and Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS). This work demonstrates that the combination of SEC and MALDI techniques is necessary for an accurate identification of the composition and molar mass of the oligomeric species present in the continuous phase of a dispersion polymerization that cannot be achieved by using either SEC or MALDI alone. For the particular latexes analyzed in this work it was found that unreacted macromonomer was present in both copolymer systems. However, in the case of the copolymerization with AN besides the presence of the macromonomer there were also some pAN oligomers.