Self-Assembly Kinetics Enhancement in Ternary “Wet Brush” Block Copolymer/Homopolymer Blend Thin Films

In this talk we discuss our recent work investigating the enhanced ordering kinetics in thin film ternary blends of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymers with low molecular weight “wet brush” PS and PMMA homopolymers that distribute more uniformly throughout the domains. In lamellar thin films, blending dramatically increases the power law exponent governing the development of long-range order during thermal annealing. For cylinders the impact of blending is more dramatic in films thicker than one monolayer due to rapid early stage ordering and faster domain reorientation with respect to the substrate. This blending strategy is also compatible with solvent vapor annealing, where it is applied to promote rapid self-assembly of ultrahigh molecular weight PS-b-PMMA (> 1000 kg/mol). The robust enhancement in ordering kinetics afforded through wet brush homopolymer blending is attributed to changes in the effective segregation strength.