Morphological studies of poly(styrene)-block-poly(ethylene-co-butylene)-block-poly(methyl methacrylate) in the composition region of the "knitting pattern" morphology

To investigate the stability of the knitting pattern (kp) morphology in pol y(styrene)-block-poly(ethylene-co-butylene)-block-poly(methyl methacrylate) (SEBNI) triblock copolymers, several SEEM with slightly different composit ions have been synthesized. Sample preparation was done by solvent casting and melt processing techniques. Morphological investigations using transmis sion electron microscopy (TEM) on films cast from chloroform revealed that several polymers exhibited the kp morphology. Polymers with a higher poly(s tyrene) content and the same amount of poly(ethylene-co-butylene) as the kp polymers exhibited predominantly a lamellar morphology from chloroform cas t films. Symmetric SEEM polymers with a decreased midblock content in films from chloroform resulted in a cylinder-between-lamellae (Ic) morphology. M elt processed samples,exhibited a predominantly co-continuous-like structur e with a mixture of layerlike and cylindrical poly(ethylene-co-butylene) mi crophases between poly(styrene) and poly(methyl methacrylate). Samples that have been cast from chloroform prior to compression molding displayed pred ominantly the kp morphology. Additional morphological investigations on sam ples cast from toluene and roll-cast from chloroform were conducted, which lead to some features of the kp morphology.