Crystalline Block Copolymers

Abstract

Most of the polymer blends, grafts, and blocks examined in the preceding chapters formed two amorphous phases. When one phase was plastic and stiff, and the other rubbery and soft, we observed that toughened materials resulted. In this chapter we examine several types of block copolymers in which one or both components crystallize; in particular we consider three possible combinations of such blocks:

• 1 A glassy/crystalline combination in the form of polystyrene/poly-(ethylene oxide), PS/PEO. This block copolymer, which has been examined in some detail in the literature, will also serve as a model system.

• 2 A rubbery/crystalline combination consisting of poly(dimethyl siloxane)/poly(diphenyl siloxane). The crystalline, high-melting diphenyl siloxane blocks alternate with rubbery dimethyl siloxane blocks, and the resulting copolymer behaves like a thermoplastic elastomer.

• 3 A crystalline/crystalline combination, polyethylene/polypropylene. This type of crystalline/crystalline block copolymer is sometimes referred to as a “polyallomer.”