TiCl3/AlEt

Catalyst I TiC /MgCVdibutylphtalate + AlEt3/phenyltriethoxysilane catalyst II TiCLt/MgCV ethylbenzoate + Al(i-Bu)3/ethylanizate catalyst III TiCl3 + AlEts Polymerization temperature... 

The free radical polymerization is probably initiated by the reaction of the peroxide with a metal—carbon bond which has been modified through complexation, solvation, or even chemical interaction with a proper monomer. This "site is interacted with the peroxide molecule, which is then decomposed in a metal-catalyzed manner to form a free radical terminus on the polymer chain along with an inert metal—peroxide interaction product. Whether the metal in question is aluminum, titanium, or a complex of the two is uncertain since the mechanism of Ziegler type reactions is still uncertain and since all three have been found in separate studies to promote the polymerization of methyl methacrylate in the presence of peroxides. However, the complex between AlEt>Cl and TiCl3 has been observed to have a much greater effect in accelerating the polymerization of methyl methacrylate than either component by itself hence, the complex appears to be the most likely species. 

There is some disagreement as to how firmly metal alkyls are adsorbed on titanium trichloride. Keii et al. [112] state that AlEtj is removed by washing with hydrocarbon solvent with loss of polymerization activity which is restored by the addition of further AlEts- Natta [81] found that washed catalyst contained substantial amounts of adsorbed aluminium alkyl and retained its polymerization activity. Chien [86] likewise concluded that treatment of TiCl3 with AlEtjCl resulted in surface alkylation. With the precipitates from TiCl4 and aluminium alkyls there are similar discrepancies. Most data (Table 1) show the presence of substantial amounts of adsorbed alkyl, but Saltman et al. [41] and Tepenitsyna et al. [225] both reported that washing with hydrocarbon solvent removed adsorbed aluminium alkyl and polymerization activity. ... 

Catalysts (a) VClj/AlEts, (b) 7-TiCl3/Al(i-Bu)3. 3-Methylbutene has been observed to polymerize at ca. 25 g polymergTiCls h" at 60°C in bulk with TiCl3/Al(i-Bu)3 [316]. This corresponds to kpf = 1.7 x 10 1 mole" sec much lower than values reported for linear a-olefins. 

Cyclodextrins treated with MAO or AlMes serve as supports for Cp2ZrCl2—AlMes or Cp2ZrCl2—MAO catalysts in ethylene polymerization.Additional alkylaluminum (AlMes, AlEts, or MAO) is needed to obtain meaningful activity from the catalyst. Polystyrene is formed when Cp TiCl3 is the metal component. Talc treated with MgR2 complexes, then with... 

In the build-up period of the decay-type Ziegler-Natta polymerization of propylene, the rates are found to be different when propylene is introduced after TiCl3 and AlEts are allowed to equilibrate from the... 

Styrene can be polymerized to stereoregular structures by coordination catalysts. Highly isotactic polystyrene is prepared using Ziegler-Natta-type catalysts obtained from the reaction between TiC and AlEts [104,105] and of a TiCl3/Al(i-Bu)3 mixture [106] in a temperature range of 0°C to 10 °C. The Al/Ti ratio has to be 3 1 for the formation of isotactic polystyrene [107,108]. A detailed description of preparations for isotactic polystyrene is given in Ref. [109]. 

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