Supporting Effects of Methylaluminoxane on the Living Polymerization of Propylene with a Chelating (Diamide)dimethyltitanium Complex

✍ Scribed by Hitoshi Hagimoto; Takeshi Shiono; Tomiki Ikeda

• Book ID: 102482421
• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 155 KB
• Volume: 205
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200350079

✦ Synopsis

Abstract

Summary: Modified methylaluminoxane (MMAO), from which free AlMe~3~ and Al(__i__Bu)~3~ were reduced to ca. 0.1 mol‐%, was supported on metal oxides, such as anhydrous silica gel, alumina, or magnesia; the metal oxide‐supported MMAO prepared were used as cocatalysts for propylene polymerization combined with a chelating (diamide)dimethyltitanium complex. The systems conducted living polymerization of propylene at 0 °C regardless of the support for MMAO. The propagation rate constants (k~p~) of these systems and the molecular weight distribution ($\overline M _{\rm w} {\rm /}\overline M _{\rm n}$) of the produced polymer depended on the metal oxide employed. The XPS analysis of the supported MMAOs suggested that the k~p~ value increased with the Lewis acidity of MMAO on the support and the broadening $\overline M _{\rm w} {\rm /}\overline M _{\rm n}$ was ascribed to the distribution of k~p~ caused by the heterogeneity of the supported cocatalyst.

Plots of \overline M _{\rm n} and \overline M _{\rm w} {\rm /}\overline M _{\rm n} against polymerization time in propylene polymerization with [ArN(CH~2~)~3~NAr]TiMe~2~: MMAO/SiO~2~ system, \overline M _{\rm n} (•), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (○); MMAO/Al~2~O~3~ system, \overline M _{\rm n} (▴), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (▵); MMAO/MgO system, \overline M _{\rm n} (▪), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (□); corresponding homogeneous system, \overline M _{\rm n} (▾), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (▿).

imagePlots of \overline M _{\rm n} and \overline M _{\rm w} {\rm /}\overline M _{\rm n} against polymerization time in propylene polymerization with [ArN(CH~2~)~3~NAr]TiMe~2~: MMAO/SiO~2~ system, \overline M _{\rm n} (•), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (○); MMAO/Al~2~O~3~ system, \overline M _{\rm n} (▴), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (▵); MMAO/MgO system, \overline M _{\rm n} (▪), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (□); corresponding homogeneous system, \overline M _{\rm n} (▾), \overline M _{\rm w} {\rm /}\overline M _{\rm n} (▿).