REINFORCEMENT OF POLYMER INTERFACES WITH RANDOM COPOLYMERS

We demonstrate that long random copolymers (monomer fraction f = 0.48) can be more effective than a long symmetric block copolymer in streng thening interfaces between immiscible homopolymers. The effectiveness of the random copolymer is inferred to result from each random copolym er crossing the interface multiple times, entangling with the homopoly mer on either side of the interface; as f is increased from 0.48 to 0. 77, the effectiveness decreases markedly as the copolymer becomes less entangled with the homopolymer (corresponding to the minor component in the copolymer) on one side of the interface.