Copolymerization of 1,3-dienes with CpTiCl3-MAO. Some cases in which the mode of monomer coordination affects the copolymer structure
✍ Scribed by Giovanni Ricci; Lido Porri
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 461 KB
- Volume
- 198
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
The following pairs of monomers were copolymerized using the catalyst system CpTiClJmethylaluminoxane (MAO): 1,3-butadiene/(E)-1,3-pentadiene, 1,3-butadiene/4methyl-1,3-pentadiene and 4-methyl-l,3-~entadiene/(Z)-1,3-pentadiene. The copolymers were characterized by NMR and infrared examination. 4-Methyl-] ,3-pentadiene/(Z)-l,3pentadiene and 1,3-butadiene/(E)-1,3-pentadiene gave copolymers having a composition intermediate between that of an ideal and that of an alternating copolymer. 1,3-Butadiene/4-methyl-1,3-pentadiene gave block copolymers only. These results have been interpreted on the basis of a different mode of coordination of the monomers. The cis-q4 coordination is by far the most stable for 1,3-butadiene and (a-1,3-pentadiene, while for (3-1.3-pentadiene and 4-methyl-1,3-pentadiene there is probably an equilibrium between the cis-q4 and trans-# form. Both these forms are reactive in the case of (Z)-1,3-pentadiene, while only the trans-$ form is so in the case of 4-methyl-l,3-pentadiene.