关键词: PS/PMMA共混物薄膜, 相逆转, 基板界面, 界面张力

Abstract: The effect of substrate on the phase morphologies of PMMA/PSblend films was investigated by means of phase contrast microscope. PMMA/PSblend films were cast onto various substrates(such as glass substrate and PPsubstrate) by spin-coating with thickness of about 10 μm. It was observed that there was a large difference of the phase inversion region between the blend films cast on glass and on PPsubstrates. On glass substrate, the phase inversion occurred at about Φ_m=04(PSmass fraction) while at Φ_m=05 on PPsubstrate. This implies that there is a shift of the phase inversion region with the change of substrate in cast polymer blend films. In other words, phase inversion region depends on the substrate. ATR-FTIRanalysis was used to detect the composition of the surface and the bottom of the films(about 100 μm thick) obtained by evaporating solvent from the polymer blend solution. The ATR-FTIRspectra of the surface and the bottom of the PMMA/PSblend thin films cast on glass substrate and PPsubstrate showed that PMMAcomponent preferentially segregated to glass substrate and PScomponent was enriched on the PPsubstrate. This selective segregation was due to the difference of the wetting abilities of PSand PMMAon the two kinds of substrates. The polymer-substrate interfacial tension γ were calculated and the results supported the ATR-FTIRresults. It could be inferred that the shift of the phase inversion region with the change of the substrate in PMMA/PSblend film was due to the fact that the composition of the blend in the bulk changed, owing to the selective enrichment of one component of polymer blend to the substrate. In other words, the affinity between polymer and substrate can strongly influence the phase morphologies and the phase inversion region in polymer blend films.

Key words: PMMA/PS blend films, Phase inversion, Substrate, Interface tension