On the properties and thermal conversion of ladder polymers with conjugated bonds

The cationic polymerization of vinylacetylenes can be implemented using an excess of catalysts, such as BF3O(C2H5)2, SnCl4, H2SO4, CCl3COOH, CF3COOH (20–50 mol per 100 mol monomer). This is due to the formation of a charge‐transfer complex between the catalyst and the polymer obtained, which was confirmed by UV, ESR and IR spectra. Polymers with conjugated ladder sequences in the chain (LP) (4) were prepared using vinylacetylene (1a), 1‐hexen‐3‐yne (1b), 2‐methyl‐1,5‐hexadiene‐3‐yne (3a), 2‐methyl‐5‐hexen‐3‐yn‐2‐ol (3b) or 5‐methoxy‐5‐methyl‐1‐hexen‐3‐yne (3c). The polymers obtained (molar mass = 2000–7000) are pale yellow to pale brown powders which display properties characteristic of polymers with conjugated bonds, i.e. thermal stability in vacuum and air, continuous absorption in UV and near visible regions, broad fluorescence spectra, electric conductivity and ESR signals. The effect of heat treatment in vacuum and air on the structure and some electrophysical properties of LPs was studied by IR, luminescence, ESR and mass‐spectroscopy and also by TGA, DTA, and X‐ray diffraction analyses. The heat treatment in the temperature range of 150–400°C gives rise to a complete cyclization accompanied by a partial degradation and leads to the formation of polycondensed aromatic structures and to a sharp increase of electroconductivity up to 1.10−5Ω−1cm−1 and to an increase of the concentration of paramagnetic particles up to 1.1020 spin/g at an ESR signal width in vacuum of 0,4 gauss (0,4.10−4 tesla). Die kationische Polymerisation von Vinylacetylenen kann mit überschüssigen Katalysatoren wie BF3O(C2H5)2, SnCl4, CCl3COOH, CF3COOH (20–50 mol pro 100 mol Monomer) durchgeführt werden. Dies ist auf eine Charge‐Transfer‐Komplexbildung zwischen Katalysator und entstandenem Polymer zurückzuführen, was durch UV‐, ESR‐ und IR‐Spektren bestätigt wird. Durch die Polymerisation von Vinylacetylen (1a), 1‐Hexen‐3‐in (1b), 2‐Methyl‐1,5‐hexadien‐3‐in (3a), 2‐Methyl‐5‐hexen‐3‐in‐2‐ol (3b) oder 5‐Methoxy‐5‐methyl‐1‐hexen‐3‐in (3c) werden Leiterpolymere (4) mit Konjugation in der Kette gewonnen. Die gewonnenen Polymere (Molmasse = 2000–7000) sind hellgelbe bis hellbraune Pulver mit den für konjugierte Polymere charakteristischen Eigenschaften, wie z. B. Wärmestandfestigkeit im Vakuum und in Luft, Absorption im ultravioletten und nahen sichtbaren Bereich, breites Fluoreszenzspektrum, elektrische Leitfähigkeit und ESR‐Signale.