Film Thickness Dependence of Phase Separation and Dewetting Behaviors in PMMA/SAN Blend Films

Film thickness dependence of complex behaviors coupled by phase separation and dwelling in blend [poly(methyl methacrylate) (PM MA) and poly(styrene-i an-acrylonitrile) (SAN)] filins on silicon oxide substrate at 175 degrees C was investigated by grazing incidence ultrasmall-angle X-ray scattering (GIUSAX) and in situ atomic force microscopy (A FM) It was found that the dewetting pathway was under the control of the parameter U-q0/E, which described the initial amplitude of the surface undulation and original thickness of film, respectively Furthermore, our results showed that interplay between phase separation and dewetting depended crucially on film thickness Three mechanisms including dewetting-phase separation/wetting, dewetting/wetting-phase separation, and phase separation/wetting-pseudodewetting were discussed in detail In conclusion, it is relative rates of phase separation and dewetting that dominate the interplay between them