Polyethylene Waxes: Catalytic Synthesis by Ti‐Biphenolates

Abstract

Soluble complexes of Ti (IV) bearing biphenol groups such as 1,1 0 -binaphthelene 2, 2 0 diol (Binol), 1,1 0 -methylene di-2-naphthol, biphenol were prepared and characterized. These catalyst precursors formulated as [Ti(O-O)(OPr i )Cl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et 3 Al 2 Cl 3 ) as co-catalyst. The ultra low-molecular weight polyethylenes are linear, crystalline and display narrow polydispersities. The PE waxes obtained with this catalytic system exhibit unique properties that have potential applications in surface coating and adhesive formulations.

Use of Titanium Complexes Bearing Diphenolate or Calix[n]arene Ligands in α-Olefin Polymerization and the ROP of Cyclic Esters

“…Table 5. Effect of the reaction conditions on the ethylene polymerization promoted by 15 [11]. In all cases, low molecular weights and narrow polydispersities were observed (900-3200 Da and 1.3-1.7, respectively).…”

“…In fact, while the amount of collected polymer doubled in the case of the reaction performed at 0 • C, no improvement was observed in the test carried out at higher temperature (Table 11, entries 6 and 10). Finally, the effect of different Al-alkyl co-activators was studied (Table 11, entries [11][12][13][14]. Interestingly, the efficiency of the process was shown to follow the trend: AlEt 3 > Al(iBu) 3 > AlEt 2 Cl> Al(iBu) 2 Cl.…”

“…The poor performance of catalyst 4 was explained considering the higher flexibility of the sulfur and tellurium-containing ligands over the more rigid methylenebridged congener. Subsequently, Trivedi et al reported the synthesis of titanium-isopropoxide complexes bearing various substituted methylene-bridged diphenols- (11)(12)(13) and binaphthols (14-15) ( Figure 5) [10,11]. In a preliminary investigation, all complexes activated by ethylaluminum sequichloride (EASC) were tested in the polymerization of ethylene (Table 4).…”

“…Titanium complexes bearing methylene-bridged diphenol and binaphthol derived ligands [10,11]. Furthermore, the effect of the reaction conditions on the performance of complex 15 in the polymerization of ethylene was investigated ( Table 5) [11].…”

“…Titanium complexes bearing methylene-bridged diphenol and binaphthol derived ligands [10,11]. Furthermore, the effect of the reaction conditions on the performance of complex 15 in the polymerization of ethylene was investigated ( Table 5) [11]. A drop of activity was observed when EASC was replaced by other Al-based co-catalysts ( Table 5, entries 1-5) Lower activities were also observed by reducing the temperature ( Table 5, entries 6 and 7).…”