THE ORGANIZATION OF CHOLESTERIC SPHERULITES

Germs of cholesteric liquids were studied in classical mixtures of nematic compounds (MBBA, PAA) with a twisting substance (cholesterol benzoate). These germs were also studied with different polymers of biological interest: synthetic polypeptides (PBLG), nucleic acids (DNA) and polysaccharides (xanthan). Germs are either spherical or elongated with a uniform orientation of layers; there are spherulites which are intermediate between these two types. The molecular orientations are continuous in the bulk of all germs, even in the presence of a disclination radius. In this case a continuous model of the disclination core is presented. The whole topology of germs is discussed and modelled. The only discontinuities are to be found at the interface only in the case of definite angular conditions. The occurrence of spherulites in biological systems is reviewed.