Thermal transformations of oligoarylenes, relating to polymers with conjugate systems, have been investigated in air and in vacuo, depending on the molecular weight and degree of branching of the original material. The extreme character of the thermostability in air versus the M-n value of oligoarylene, and the possibility of increasing the thermal oxidative stability by enhancing the degree of branching have been explained by different intensities of intermolecular processes of dehydropolycondensation in the period before the starting of substantial weight losses. The influence of the solidification (or carbonization) conditions of the oligoarylenes on the structures and thermooxidative stabilities of the resulting samples was studied.Oligoarylenes deserve attention with a view to creating polymer systems which display high thermal stability [1 ]. In the present work thermal transformations of oligoarylenes (based on condensed aromatic compounds) were investigated in air and in vacuo, at 20-800 ~ depending on Mn and the degree of branching in the starting material. The effects of the solidification (or carbonization) conditions (heating rate and final temperature) on the thermooxidative stability and structure of the resulting products were also__investigated. These investigations were carried out for oligoarylenes of various M, values and degrees of branching.

Soluble oligoarylenes based on naphthalene and anthracene, and fractions of different molecular weights have been studied by electron microscopy. For the examined samples, a definite interrelation is ascertained between microstructure and physicochemical properties, such as density, x‐ray parameters, heat of solution, electron paramagnetic resonance (EPR) spectra, and dark conductivity. The molecular‐weight distribution of oligoarylenes is shown to decisively influence the degree of packing of macromolecules and their physicochemical properties. This allows interpretation of some anomalous properties of oligoarylenes in comparison with the first members of the corresponding homologous series.

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