Polymerization of Methyl Methacrylate Initiated by a Divalent Samarium Phenoxide Complex with an Alkyl Aluminium Compound

✍ Scribed by Mitsufumi Nodono; Toru Tokimitsu; Takayuki Makino

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 131 KB
• Volume: 204
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200390053

✦ Synopsis

Abstract

A divalent samarium complex that bears two bulky phenoxide ligands promotes the living polymerization of methyl methacrylate in the absence of cocatalyst. The initiation involves a tail‐to‐tail coupling reaction of the samarium‐enolate radical followed by a one‐electron reduction of the monomer with the divalent samarium initiator. The polymerization takes place stereospecifically and the samarium initiator affords highly syndiotactic poly(methyl methacrylate). The stereoregularity of the polymer is variable with the ratio of the samarium initiator to aluminium compound (2,6‐di‐tert‐butyl‐4‐methylphenoxy)~2~AlMe. The polymer obtained when the [Al]/[Sm] ratio is 4.0 has a unique tacticity, [mm]/[mr]/[rr] = 42:11:47, and the polymer has a melting point at 161 °C, which suggests the formation of a stereocomplex between syndiotactic and isotactic poly(methyl methacrylate).

Part of the possible initiation mechanism and equimolar reaction of BHT‐Sm^II^ with MMA.

magnified imagePart of the possible initiation mechanism and equimolar reaction of BHT‐Sm^II^ with MMA.