KINETICS OF GROWTH OF ISLANDS AND HOLES ON THE FREE-SURFACE OF THIN DIBLOCK COPOLYMER FILMS

When prepared on a silicon wafer and annealed above the glass transiti on temperature T(g), symmetric, diblock copolymers of poly(styrene-b-b utylmethacrylate), P(S-b-BMA), exhibit a multilayer structure parallel to the substrate and islands (or holes) are formed on the free surfac e of the films. In situ interference microscopy has been used to follo w the kinetics of growth of these islands or holes. It is shown that t he kinetics of growth depends on the initial density of islands (or ho les) : at 140-degrees-C, for intermediate annealing times, there is no time-evolution of the free surface for dilute systems while for more concentrated ones, the size distribution function of islands or holes verifies a scaling law versus time. For longer annealing times at 170- degrees-C, the ultimate behavior of the copolymer film is to eliminate islands or holes by allowing the permeation of the copolymer molecule s into the inner layers of the film.