ABSTRACT:High-resolution pyrolysis~gas chromatography was successfully applied to characterize the end groups of poly(methyl methacrylate) (PMMA) prepared by radical polymerization. Although PMMA mainly depolymerized to the monomer at elevated temperatures, some of the minor peaks on the pyrograms could be assigned to the products associated with the end groups derived from both the initiation reactions caused by benzoyl peroxide (BP0) and the chain transfer reactions to dodecanethiol and solvent. Two kinds of BP0-initiated chain ends were clearly distinguished. It was confirmed that phenyl-initiated polymer chains rather than benzoyloxyinitiated ones were prefeTentially formed in solution polymerization, whereas the latter predominated in bulk polymerization. Moreover, the characteristic peak intensities could be correlated to the amounts of polymerization reagents in the feed. In addition, dodecanethiol formed from thiol-incorporating chain ends was selectively detected without interference from any other pyrolysis products by using a sulfur-specific flame photometric detector.
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