Isotactic trans‐1,4 polymers of 1,3‐pentadiene

Abstract

Crystalline polymers of 1,3‐pentadiene, which are composed of trans‐1,4 units and show an isotactic configuration of the tertiary carbon atoms, have been obtained with the use of the heterogeneous Al(C2H5)3VCl3 catalytic system. The cis or trans isomer of pentadiene yields polymers that are more stereoregular than those obtained from mixtures of the two isomers. Isotactic trans‐1,4‐poIypentadiene may exist in two modifications: crystalline and paracrystalline (unidimensionally regular). The two modifications are characterized by different x‐ray spectra and different densities. trans‐1,4 Isotactic polypentadienes contain tertiary carbon atoms which are actually asymmetric. This permitted obtaining optically active polypentadienes by using polymerization catalysts prepared from optically active aluminum trialkyls.

A new insight into the mechanism of 1,3‐dienes cationic polymerization. II. Structure of poly(1,3‐pentadiene) synthesized with tBuCl/TiCl4 initiating system

“…Indeed, a large number of studies are devoted to the investigation of microstructure of PPD . The microstructure of stereoregular PPDs synthesized by stereospecific polymerization of 1,3‐pentadiene was already studied in detail.…”

“…The microstructure of stereoregular PPDs synthesized by stereospecific polymerization of 1,3‐pentadiene was already studied in detail. In early investigations directed to the structure of these PPDs, IR‐spectroscopy or IR‐spectroscopy in a combination with 1 H NMR spectroscopy was initially used . Then, 13 C NMR spectroscopy was chosen as a powerful tool for analysis of the microstructure of stereoregular PPDs .…”

Normal Coordinate Analysis for Polymer Systems: Capabilities and New Opportunities

“…The preferred conformation of TPDCB, as determined by X-ray diffraction by Chatani et al, [50] is monoclinic, similar to that of other trans-polybutadienes. [51][52][53] This X-ray structure, along with several assumed values for bond lengths, was used to obtain the structure of a single chain. As Petcavich and Coleman point out, since the monomer unit has C i symmetry, there is mutual exclusion between IR active (symmetry species A u ) and Raman active (symmetry species A g ) modes, which are assigned with the help of total energy decomposition.…”

Ziegler–Natta Catalysis

“…3-Methyl-fra«s-l,3-pentadiene can be polymerized to greater than 97% of the ds-l,4-isomer by a catalyst made up of TiCl 4 , triisobutylaluminium and diphenyl ether. 124 Isotactic fra«s-l,4-polypentadiene ( Figure 25) can be produced using TiC^ and triethylaluminium, 125 while isotactic c/s-l,4-polypentadiene is produced in poor yield when titanium tetraalkoxides form the titanium component. 1,4-Polycyclopentadiene can be obtained using a catalyst comprising TiCl 4 and a trialkylaluminium.…”