Influence of coagulation process on solid‐phase structure of poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene): non‐solvent induced crystallization

A preliminary investigation on the influence of the coagulation process on the solid‐phase structure of poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) (1) is reported. Interesting correlations between the method of coagulation of the polymer from sulfuric acid solution and the structure which develops, as observed by thermal analysis, X‐ray diffraction, infrared spectroscopy, and optical microscopy are found. A new method for the preparation of highly crystalline spherulites of 1 is described. This method allows to grow a relatively large number of “single spherulites”, because coagulation and crystallization induced by a non‐solvent may be stopped before impingements occur.