Two poly (2,5-thienythiazolothiazole)s: Observation of spontaneous ordering in thin films

The synthesis and properties of two new polymers based on thiazolothiazole are described. The polymers dissolve in common organic solvents such as chloroform and chlorobenzene. Their molecular weights are in the kDa range with polydispersities on the order of 1.1-1.3 as determined by GPC. The X-ray crystal structure of one monomer was determined. Interplanar pi-pi interaction and short S center dot center dot center dot N contacts (3.20 angstrom) were observed in the crystal. The monomers and polymers strongly fluoresce in Solution. Their quantum yields range from 23 to 55% relative to 9,10-diphenylanthracene and rhodamine B. Contrary to expected polymer behavior, the polymers are unusual in that they self-assemble upon drop-casting. The thin films of polymers exhibited sharp reflection peaks in the low-angle region in XRD measurement, indicating a highly ordered assembly.