MOLECULAR MECHANICS OF PHOTOPOLYMERIZATION OF 2,5-DISTYRYLPYRAZINE IN SOLID STATE.

The molecular mechanics of photopolymerization of 2,5-distyrylpyrazine in the solid-state alpha form is investigated by a combination of Raman and electronic spectroscopic techniques. A stepwise photoreaction is used to stabilize an intermediate oligomer structure. For this purpose, the 476. 5-nm argon-ion laser line is used to convert the monomer to the oligomer. The Raman phonon spectra reveal a homogeneous mechanism, with considerable lattice rearrangement, for the oligomerization process, which is also found to produce lattice strain. The Raman phonon spectra, monitored during the conversion of the oligomer to the polymer, show that initially the process starts homogeneously, with considerable lattice rearrangement. Then it turns heterogeneous, with a phase separation accompanied by a gradual ordering of the polymer product lattice.