Synchrotron radiation X-ray diffraction study of polymorphic crystallization of SOS from liquid phase

Kinetic properties in polymorphic crystallization of SOS(1,3-Distearoyl-2-o leoyl-sn-glycerol) in a melt-mediated transformation have been examined in situ with a time-resolved (10 s intervals) X-ray diffraction method using s ynchrotron radiation (SR-XRD). It was observed that the formation of lamell ar ordering occurred more rapidly than that of the lateral subcell packing, as revealed in the sequential occurrence of SR-XRD long spacing and short spacing spectra. The time lag in the occurrence of the two spectra increase d with increasing stability of the polymorphic forms which crystallized; e. g., the formation of the stable chain packing of T-parallel to in a stable beta polymorph was delayed by 500 a from the formation of the lamella, yet the time lag was 10-20 s in the crystallization of a metastable beta' form. This behavior was singly detectable by the SR-XRD,not by a conventional XR D technique. (C) 1999 Elsevier Science B.V. All rights reserved.