ORDERING AND STRUCTURE FORMATION IN TRIBLOCK COPOLYMER SOLUTIONS .2. SMALL-ANGLE X-RAY-SCATTERING AND CALORIMETRIC OBSERVATIONS

The morphology and thermal properties of a poly(styrene)-poly(ethylene , butylene) triblock copolymer in the presence of a selective solvent has been investigated, using small-angle X-ray scattering (SAXS) and c alorimetry (d.s.c.). The temperature dependence of the SAXS profiles i ndicated a transition, which was associated with a thermal destruction of the superlattice, preserving the nearest neighbour distance betwee n the micro domains. The transition temperature was referred to as the disordering temperature (T-d). On heating, the loss of long range ord er was observed as a sudden broadening of the line profiles of the fir st order peak. At higher temperatures a gradual disappearance of this first order peak was interpreted as a gradual dissolution of the micro domain structure. Simultaneously, calorimetric investigations reveale d two transitions on heating: at lower temperatures a glass transition , followed by an endothermic transition. The onset of the endotherm co rresponded to T-d. In addition, the onset of how, which has been repor ted in Part I of this series, also corresponded to T-d Annealing at in termediate temperatures resulted in the formation of large scale order ing. This ordering could be followed by X-ray scattering and correspon ded to changes observed in the rheological behaviour. (C) 1997 Elsevie r Science Ltd.