Characterization of substituted polyacetylene microstructure by pyrolysis gas chromatography

Autor: Jiri Vohlidal, Jan Sedláček, Róbert Kubinec, Vera Pacakova, Z. Doležal
Rok vydání: 2007
Předmět:
Zdroj: Journal of Separation Science. 30:731-739
ISSN: 1615-9314
1615-9306
DOI: 10.1002/jssc.200600388
Popis: A series of substituted acetylenes has been polymerized with WOCl 4 /Ph 4 Sn metathesis catalyst and [Rh(cod)OMe] 2 insertion catalyst, and the thermal degradation of the polyacetylenes prepared has been studied using pyrolysis capillary gas chromatography (Py-GC) with flame ionization and mass spectrometric detection to obtain information on the effect of the catalyst on the head-tail (H-T) isomerism of polyacetylenes (poly(phenylacetylene), poly[(4-methylphenyl)acetylene], poly(benzylacetylene), poly[(2-fluorophenyl)acetylene(, poly((3-fluorophenyl)acetylene], and poly[(4-fluorophenyl)acetylene]). Cyclotrimers have been found to be the main pyrolysis products in all cases. Direct Py-MS connection was used to determine the temperature profiles of the released pyrolysis products. 1,3,5-Trisubstituted benzenes were found to be the predominant pyrolysis products of the polymers prepared with the insertion catalyst, which proves the presence of long head-to-tail sequences of monomeric units in these polyacetylenes. On the other hand, both 1,2,4- and 1,3,5-trisubstituted benzenes are present in significant amounts in the pyrolysis products of polymers prepared with the metathesis catalyst, which proves the presence of a significant content of the head-to-head (HH) and tail-to-tail (TT) linkages in these isomers of polyacetylenes. Contents of the regular (HT) and inverse (HH-TT) monomer linkages (RML and IML, respectively) in polymer chains were determined from the relative amounts ofdi-, tri-, and tetrasubstituted benzenes found in the Py-GC products.
Databáze: OpenAIRE
Externí odkaz: