Complementary Characterization of End Groups in Radically Polymerized Poly(methyl methacrylate) by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry and Pyrolysis-Gas Chromatography-Mass Spectrometry

Abstract

e end groups in radically polymerized poly(methyl methacrylate) samples with tert-butyl peroxy-2-ethyl-hexanoate as an aliphatic peroxide initiator and 1-octanethiol as a chain transfer reagent were complementarily characterized by high-resolution matrix assisted laser desorption/ionization (MALDI) spiral time-of-ight mass spectrometry (MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). e end groups comprised of three types of the initiator fragments and octylthio group originating from the chain transfer agent were connrmed by MALDI-MS measurements. In addition, their quantitative information was obtained by Py-GC-MS. Furthermore, combined with size exclusion chromatographic fractionation, the molar mass dependence of the end groups in the PMMA samples was also examined. It was suggested that the relative content of the octylthio end groups might increase with increase in the molar mass of the fractions. e observed results were interpreted in terms of the polymerization reactions of the PMMA samples.