Approaches to conjugated polymers via solid state polymerization

Topochemical solid state polymerization is a method of obtaining fully crystalline macromolecules. Herein, approaches to conjugated polymers via new solid state polymerizations and the properties of materials, especially polydiacetylenes(PDA), obtained via solid state polymerization are discussed. Our attempts to polymerize cyanoalkynes and to define the thermal reaction product of a dicyanodiazepine are presented. Certain PDA exhibit absorption, likely charge-transfer, at energies below the exciton. Nanocrystals of PDA-DCH react with liquid bromine to give the mixed polyacetylene PDA-DCHBr₆ whose visible spectrum exhibits structure not observed in spectra of bulk crystals of PDA-DCHBr₆. The thermochromic PDA of the dialkylurethanes of 5,7-dodecadiyn-1,12-diol were studied by variable temperature solid state ¹³C nmr. The upfield shift of the acetylene carbons as the temperature is raised above that of the thermochromic phase transition indicates the role of mechanical strains in achieving thermochromism.