Solid State Polymerization and the Chemical Reactivity of Solid Polydiacetylenes

Abstract

The term “design” of a solid state polymerization, taken to imply the necessary crystallographic and mechanistic considerations, is introduced with a view toward discovery and development of new lattice controlled processes. Using examples from known solid state polymerizations, a qualitative discussion of several crystallographic and mechanistic issues is presented. With the caveat that such issues may not be easily separated, a central conclusion appears to be that mechanistic problems associated with initiation and propagation steps may hold the key to progress in this area. While chlorine, aqua regia, and nitric acid convert single crystals of poly-1, 6-di-N-carbazolyl-2, 4-hexadiyne (DCH) to amorphous solids, bromination, which proceeds more rapidly as temperature is lowered, results in a crystalline solid. These reactions are anisotropic and their products are characterized by spectroscopic and crystallographic techniques. It is concluded that the initial reactivity is controlled by carbazole energy levels, rather than those of the conjugated backbone.