Self-assembling study of a cylinder-forming block copolymer via a nucleation–growthmechanism

Abstract

Block copolymer materials form self-assembling structures at a nanometric scale, of interest innanotechnology. The organization process of asymmetric poly(styrene-block-methyl methacrylate)(PS-b-PMMA) copolymer thin films is studied. In a first step it is demonstrated that twoconsecutive mechanisms lead to the formation of a well-ordered phase. The first mechanismis the local segregation of blocks, which leads to a metastable disordered cylinder phase(Cd). The second mechanism is a transformation of theCd phase to a vertical cylinder phase via a nucleation–growth mechanism. The influence of film thicknessand surface tension on the organization is also studied. Above the natural cylinder monolayer height,h1,the kinetics of the cylinder organization strongly depends on the initial film thickness, and belowh1 the film splits into terraces. By varying the interactions between the substrate surfaceand the different blocks, a disordered phase can be formed instead of terraces.