Reaction Kinetics of the Solid State Polymerization in Diacetylene Crystals.

We report on experimental and theoretical studies concerning the reaction kinetics of the solid state polymerization in diacetylene crystals. The individual reaction steps of the short‐chain reaction intermediates (dimer, trimer, tetramer, ...) have been investigated by time resolved ESR and optical spectroscopy. In a microscopic theory energy barriers of molecular translations and rotations as well as the mismatch of the oligomer molecules in the crystal matrix are taken into account. The ‘‘molecular‐mechanical’’ model gained in this way is successful in describing the experimentally observed dependencies of the activation energy of the addition reaction on chain length, temperature, and conversion. It also explains the time‐conversion behavior of the reaction. Moreover, we gain information about the activation energy of the total reaction and can anticipate the temperature dependency of the chain length.