Thin supported polystyrene-${\mathrm{C}}_{60}$ fullerene mixtures annealed above their glass transition temperature develop spinodal surface undulations which depend on film thickness $h(20–500\mathrm{nm})$, polymer molecular mass $M_w$, temperature, and time $t$. The dominant wavelength $\lambda \sim 1–10\mu \mathrm{m}$ scales linearly with $h$ and coarsening kinetics follow $\lambda \sim t^{\alpha }$, with $0<\alpha (h)<1/3$; the morphology eventually pins at long times. This spinodal surface excitation contrasts with dewetting suppression and film stability observed in low-$M_w$ polymers and results from the interplay of binary miscibility and fullerene substrate attraction.

• Received 23 October 2009

DOI:https://doi.org/10.1103/PhysRevLett.105.038301