Interfacial segregation in disordered block copolymers: Effect of tunable surface potentials

The response of disordered P(d-S-b-MMA) diblock copolymers to variable strength surface fields has been studied by neutron reflectivity. Surface interactions were controlled by end grafting P(S-r-MMA) random copolymers with various styrene contents onto Si substrates. The degree interfacial segregation of the block copolymer was proportional to the surface potential. A first-order transition in the degree of segregation was observed as the brush composition was varied. Conditions were found which yielded neutral boundary conditions simultaneously at the vacuum and substrate interfaces. © 1997 The American Physical Society.