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

• Published in: Macromolecular chemistry and physics Vol. 204; no. 5-6; pp. 877 - 884
• Main Authors: Nodono, Mitsufumi, Tokimitsu, Toru, Makino, Takayuki
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.04.2003; WILEY‐VCH Verlag; Wiley
• Subjects: anionic polymerization; Applied sciences; Exact sciences and technology; isotactic; living polymerization; Organic polymers; organometallic catalysts; Physical Sciences; Physicochemistry of polymers; Polymer Science; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Science & Technology; stereospecific polymers; syndiotactic; POLYMERS; REAGENTS; LEWIS-ACID; TOLUENE; SYNDIOTACTIC POLY(METHYL METHACRYLATE); syndiotactic; anionic polymerization; ANTI-CRAM; living polymerization; CARBONYL ALKYLATION; MOLECULAR-WEIGHT DISTRIBUTION; isotactic; organometallic catalysts; OBTAINING UNUSUAL EQUATORIAL; stereospecific polymers; SELECTIVITY; Samarium II Complexes; Living polymer; Methyl methacrylate polymer; Aryloxy complex; Composition effect; Complex catalyst polymerization; Complex catalyst; Experimental study; Syndiotactic polymer; Stereoregulation; Solution polymerization; Reaction mechanism; Stereospecificity; Aluminium Organic compounds; Stereospecific polymerization; Catalyst activity
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.200390053

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)2AlMe. 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‐SmII with MMA.