Phase Separation and Dewetting of Polymer Blend Thin Films

Phase separation and dewetting of polystyrene (PS) and Poly(vinyl methyl ether ) (PVME) blend thin films were studied as a function of film thickness by means of light scattering, AFM, optical microscope, and neutron reflectivity.

Characteristic wavelength as a function of film thickness

In a range of thickness above 1μm, phase separation occurs preferentially, and below 100 nm dewetting occurs preferentially. In between (100 nm - 1μm) phase separation and dewetting coexist and no characteristic length is observed in LS profiles.

NR measurements revealed that concentration fluctuations occur at interface before dewetting. This may trigger the dewetting. The above figure shows a schematic sketch of phase separation-assisted dewtting.