Studies on the Polymerization of Methyl Methacrylate with Butylmagnesium Chloride by the Aid of Totally Deuterated Monomer—Structures of Polymerization Products and Fate of Initiator

Abstract

ABSTRACT:Totally deuterated methyl methacrylate (MMA-d8) was polymerized by C4 H 9 MgCl in toluene at -78"C, and the resulting polymer and oligomer were analyzed by 1 H NMR spectroscopy. The polymer and oligomer was found to contain butyl pentadeuteroisopropenyl ketone (BJPK-d5) units. The ketone was formed by the addition of the initiator onto the carbonyl group of the monomer. The content of BIPK-d5 units in the polymer and oligomer was found to be 0.3 and 0.4 per chain, respectively. FD-and EI-mass spectra of the fractionated oligo(MMA)s indicated that most of the BIPK units were located at their terminating chain ends. Structures which were produced by intramolecular cyclization and by carbonyl addition of propagating anions onto MMA or BIPK were found at the end of the oligomer chain, but the amounts of these structures were at most I 0% of the chain. The fate of the initiator during the polymerization was clarified for the most part. From the results, the mechanism of polymerization is discussed in some detail.

Quantification of End Groups in Anionically Polymerized Poly(methyl methacrylate)s by Pyrolysis−Gas Chromatography

“…However, the recent advent of various analytical techniques has made it possible to carry out the practical studies of the end groups of polymers. The radioactive isotope labeling method has been used over a long period to determine the initiator fragment incorporated at chain ends by measuring the specific activities of radioactive samples prepared with 14 C-labeled initiator. , In recent years, high-field NMR techniques have been successfully applied to study polymer chain ends. ,− A number of reports have been published on the NMR studies of the end groups of various polymers prepared with the initiators isotopically enriched with NMR-active nuclei such as 13 C, 2 H, 19 F, and 15 N. − In contrast, Hatada et al polymerized totally deuterated methyl methacrylate (MMA) monomer with nondeuterated initiator to determine the content of the initiator fragments incorporated in the polymer chain by 1 H-NMR and discussed the mechanism of polymerization in detail. − …”