✦ LIBER ✦

Polymerization of methyl methacrylate by organometallic compounds—VI. Kinetics and mechanism of polymerization initiated photochemically by triethyl aluminum—monomer complexes

✍ Scribed by P.E.M. Allen; B.O. Bateup; B.A. Casey

Publisher: Elsevier Science
Year: 1972
Tongue: English
Weight: 507 KB
Volume: 8
Category: Article
ISSN: 0014-3057
DOI: 10.1016/0014-3057(72)90098-5

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✦ Synopsis

The initial rate of polymerization is

where Io is the incident illumination and [A12Ets]o is the total molar concentration of tfialkyl aluminium dispensed, estimated as dimer. Direct photolysis of the 1 : 1 MMA:AIEts Wittig-"ate" complex is not responsible for polymerization. Initiation is thought to occur by the bimoleeular reaction of a photo-excited state of this complex with a molecule of the complex in its ground state to form a species which then decays to radicals. Abnormally long induction and decay periods suggest a slow step prior to the formation of free radicals which then initiate a radical chain polymerization. Ethyl aluminium alkoxides that form rapidly when MMA/A1 ~< 0.5 did not polymerize excess MMA in hulk at 248 K in the dark or under ambient illumination.

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