The effect of casting temperature on morphology of poly(styrene-ethylene/butylene-styrene) triblock copolymer

The morphology of poly(styrene-ethylene/butylene-styrene) (SEBS) triblock c opolymer films cast from the solution in xylene at different temperatures w as investigated by transmission electron microscope. The SEES solution was first heated to a certain temperature, which ranges from 20 to 140 degreesC and then cast onto the surface of phosphoric acid at the same temperature to prepare specimen films. Three different kinds of morphologies including coexistence of a large number of branched cylinders and a small number of s pheres, coexistence of cylinder region and near homogenous region, and coex istence of non-branched cylinders and spheres were observed corresponding t o 20, 80-110, and 130-140 degreesC temperature zones, respectively. Moreove r, it was found that the diameter of cylinders increases with the casting t emperature. All these show an obvious casting temperature dependence of the microphase separation phenomenon. (C) 2001 Published by Elsevier Science L td.