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EnglishPolymer microstructures obtained by copolymerizations of (Z)-1,3-pentadiene with ethene, conducted at different temperatures by the CpTiCl3-MAO catalytic system, have been characterized by detailed 13C NMR analyses. The observed microstructures indicate an essential role of the backbiting of the allyl-terminated growing chain on the occurrence of 1,2 syndiotactic and 1,4-cis high selectivities, which are observed for (Z)-1,3-pentadiene homopolymerizations at low and high temperatures, respectively. Molecular modeling studies suggest that the occurrence of 1,2-syndio and 1,4-cis stereoselectivities would be determined by the steric constrain (and stereorigidity) associated with the maintenance, in monomer bound intermediates, of the backbiting coordination of syn and anti allyl-terminated growing chains, respectively.
| Titolo: | High selectivity in polymerization of (Z)-1,3-pentadiene, with the CpTiCl3-MAO catalytic system, generated by backbiting coordinations of the growing polydienyl chain. | |
| Autori: | ||
| Data di pubblicazione: | 2004 | |
| Rivista: | ||
| Abstract: | Polymer microstructures obtained by copolymerizations of (Z)-1,3-pentadiene with ethene, conducted at different temperatures by the CpTiCl3-MAO catalytic system, have been characterized by detailed 13C NMR analyses. The observed microstructures indicate an essential role of the backbiting of the allyl-terminated growing chain on the occurrence of 1,2 syndiotactic and 1,4-cis high selectivities, which are observed for (Z)-1,3-pentadiene homopolymerizations at low and high temperatures, respectively. Molecular modeling studies suggest that the occurrence of 1,2-syndio and 1,4-cis stereoselectivities would be determined by the steric constrain (and stereorigidity) associated with the maintenance, in monomer bound intermediates, of the backbiting coordination of syn and anti allyl-terminated growing chains, respectively. | |
| Handle: | http://hdl.handle.net/11386/1059747 | |
| Appare nelle tipologie: | 1.1.2 Articolo su rivista con ISSN |
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