Order to Disorder Transition Behavior of Block Copolymer Thin Films and Thickness Dependence

Abstract

We investigated thickness dependence on the phase transition behavior in cylinderand lamella-forming polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) films. An asymmetric wetting condition generates cylindrical and lamellar microdomains oriented parallel to the substrate. We evaluated the thickness dependent phase transition as a function of film thickness using ex-situ grazing incidence small-angle x-ray scattering (GISAXS). The order to disorder transition temperature (TODT) remarkably increases as the film thickness decreases less than a critical thickness above which the TODT of the films are independent film thickness. Our numerical calculation utilizing integral version of self-consistent field theory (SCFT) is qualitatively consistent with the experimental results displaying an increase in TODT of the BCP films.