"Superductile" semicrystalline ABC triblock copolymers with the polystyrene block (A) as the matrix

The relationship between the microphase morphology and stress-strain behavi or of a polystyrene-block-polybutadiene-block-poly(epsilon-caprolactone) SE C triblock copolymer has been investigated with polystyrene as the major co mponent. The semicrystalline PCL block does not change significantly the ba sic morphology, but it affects the form of the microdomains, so that S57B27 C16 shows a "polygonal" core shell morphology in a PS matrix. This morpholo gy seems to be the consequence of crystallization in the inner PCL cylinder s inducing deformation of the microdomains, which may create interfacial st resses. These stresses can generate small microcrazes upon external loading which may be responsible for the high elongations at break in this materia l. Moreover, the long-range order of the microdomains, which can be affecte d through the preparation conditions, determines the stress-strain behavior . Copolymers with 57 and 51 wt % PS and a corresponding "PS matrix" exhibit elongations at break up to similar to 800%.