Synthesis and Dilute Solution Characterization of Extended Chain Poly(Benzazoles)

This paper reports the synthesis method for polymerizaing poly(2,6-benzothiazole) (ABPBT) and poly(2,5-benzoxazole) (ABPBO), and their dilute solution properties using low angle light scattering and viscometry. Our data indicate that the Mark-Houwink-Sakurada exponents for these extended-chain polymers are near unity, suggesting a semi-rigid conformation in dilute solutions. The solution properties agree well with the Yamakawa-Fujii worm-like chain model when persistence lengths of 130 Å and 90 Å are assumed for ABPBT and ABPBO, respectively. These values of persistence length are also in good agreement with those predicted by Flory’s virtual bond model using information on the molecular geometries taken from x-ray crystallographic data on oriented fibers of ABPBT and ABPBO.