Crystallization and Gelation in the System iPS/CIS-Decalin and Intermediate Phases

Abstract

Organized structures grown from iPS/cis-decalin solutions (ranging from 5% to 50% w/w) have been studied by DSC, neutron diffraction and small-angle neutron scattering. The thermal behaviour has been investigated as a function of the annealing temperature and the temperatureconcentration phase diagram has been established. The existence of two phases between the gel state, obtained at high undercooling, and the crystalline state, obtained at low undercooling, is demonstrated. Short range molecular order determined by neutron diffraction confirm these findings. These phases are designated as the s-phase (already described by Klein et al.) and the p-phase. Except for the crystalline state all the other phases contain intercalated solvent molecules. The gel state displays nematic-like order whereas the s-phase is reminiscent of smectic arrangements. The p-phase is less solvated than the s-phase and can be regarded as a peritectic system. Preliminary neutron scattering experiments show that folding reappears in the s-phase whereas it was shown to be absent in the gel phase.