Effect of block copolymer adsorption on thin film dewetting kinetics

The stability of polystyrene (PS) films on silicon oxide is improved by ble nding with poly-(styrene-block-methyl methacrylate) (PS-b-PMMA) having a sh ort, adsorbing MMA block and long, dangling PS block (degree of polymerizat ion N). Relative to PS (degree of polymerization P), hole growth velocity d ecreases by 5 and 17 times upon adding 0.05 volume fraction of PS-b-PMMA (p hi) for N similar to P and N similar to 4P, respectively. In contrast to PS , holes approach a constant value and do not coalesce. The N similar to 4P system provides better stabilization because of its broader interfacial wid th. For N similar to P, hole velocity decreases as phi increases and then b ecomes constant for phi > 0.03. Relative to blends, holes grow faster in bi layers and eventually coalesce. AFM analysis shows that the PS hole floor i s smooth whereas the blend floor contains patches. The film stabilizing eff ect of block copolymers can be attributed to a decrease in capillary drivin g force, entanglements at the matrix/copolymer interface, and brush graftin g density.