THE FORMATION OF SUPERMOLECULAR POLYCAPROLACTONE (PCL) SPHERULITES IN POLYSTYRENE-POLYBUTADIENE-PCL (PS-b-PB-b-PCL) SEMICRYSTALLINE BLOCK COPOLYMERS

摘要

The morphological behavior of polystyrene (PS), polybutadiene (PB), and polycaprolactone (PCL) semicrystalline block copolymers as a function of annealing conditions is discussed. For this study, both bulk and thin films of (PS)_(0.35)(PB)_(0.15)(PCL)_(0.5) were cast from toluene solution and the morphologies were examined using transmission electron microscopy (TEM) and polarized light microscopy (PLM). The morphology of either as-cast or annealed bulk (1 mm) specimens is a lamellar-cylindrical morphology having PB cylinders at the interphase boundaries. The block copolymer thin film (5-10 μm) from fast solvent evaporation also shows a lamellar-cylindrical microphase-separated morphology without the formation of visible PCL spherulites using PLM. After the formation of the well-defined PCL spherulites by annealing, the micromorphology is no longer lamellar-cylindrical but instead the PCL lamellar crystals dominate the system.