Polydialkoxyphosphazenes with different substituents varying from methoxy up to octoxy which contain only minor amounts (below 0,l mol-%) of various defective units in their macromolecules were synthesized. It was shown that such polyphosphazenes with propoxy, butoxy and pentoxy side groups can exist in the mesomorphic state and that a defect content as low as about 2 mol-% prevents mesophase formation. In spite of high flexibility of the main chain, the polydialkoxyphosphazenes were found to gain the ability to crystallize only if the number of C atoms in the alkoxy substituents is higher than six.

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Cleavage reactions of perfluorinated tertiary amines in the presence of antimony pentafluoride are studied in detail.

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