The conditions for reliable preparation of bulk PB‐1 samples in form III were established. The crystal structure of solution‐prepared PB‐1 samples was measured by X‐ray diffraction as a function of solvent used, solution concentration, temperature of solution preparation, and solvent evaporation or solution precipitation. Measurements at higher temperatures revealed the crystallization of form III to I at temperatures below 95°C and to form II at temperatures above 95°C.
Acknowledgments
This research was supported, in part, by Grant ME‐131 from the Granting Agency of the Czech Republic and Grant DMR 0234678 from the Polymer and International Programs sections of the U.S. National Science Foundation.