The mechanism of the low temperature polymerization reaction in diacetylene crystals

The mechanism of the low temperature polymerization reaction in TSHD diacetylene crystals has been investigated by the transient ESR of the paramagnetic triplet (S = 1) and quintet (S ≈ 2) reaction intermediates. The reaction schemes of the thermal and optical addition and transformation reactions after UV photoinitiation are obtained. The activation energies of the chain propagation reaction and the singlet—triplet and singlet—quintet energy separations of the different dicarbene and diradical intermediates are deduced from the experiments.