Structure Formation in Solutions of Rigid Polymers Undergoing a Phase Transition

The development of morphology, when solutions of rigid polymers are transformed from the liquid to the solid state, was studied in two particular cases coagulation of a monodomain nematic solution and gelation of a dilute isotropic solution. Direct observation of the morphology by electron microscopy E.M. was augmented by measurements of small-angle X-ray scattering SAXS. A theoretical framework for the analysis of SAXS measurements from oriented systems using a slit-collimated incident beam was developed. The first case is realized in the coagulation stage of the spinning process of high performance fibers and films from solutions of rigid macromolecules. A monodomain nematic solution of poly p-phenylene benzobisthiazole PBT in polyphosphoric acid PPA undergoes a transition to the solid state by the action of a non solvent water . For the second case, gelation of an Isotropic solution of poly alpha-benzyl- 1-glutamate, induced by a decrease in temperature, was studied. Keywords Poly p-phenylenebenzobisthiazole, Morphology, Rigid Rod, Polymers, Thiazoles, Crystals, Solvate, Nematic, Coagulation, Polybenzylglutamate.