Using vhase contrast microscope

the evolution of the phase separation was investigated for poly(methyl methacrylate)(PMMA)/hyperbranched poly(ester-amide)(HBP)blend thin films on glass substrates．The films with different component ratios show different phase morphologies and phase separation processes．At a film thickness of about 500 nm．a cylinder-like dispersed phase Was observed in the films with low HBP content．The conditions for the special morphology occurring were also studied．The interaction between the substrate and HBP and the thickness of blendfilms are essentialfactors for the formation of the phase morphology．It was also found that the appearance of the special cylinder-like morphology depends on the component ratio and the fdm thickness．Only the film thickness was between the upper critical film thickness and the lower critical film thickness can the special structure be observed．There was a transition in the critical thickness as the HBP weight percent varied．