Miscibility of mixed stereoregular PMMA/PVPh monolayers at the air/water interface

The mixed monolayer behavior of stereoregular poly(methyl methacrylate) (PMMA) and poly(vinyl phenol) (PVPh) was investigated from the measurements of surface pressure–area per molecule (π–A) isotherms. The π–A isotherms indicated that isotactic PMMA (iPMMA) and PVPh were miscible at the air/water interface. The miscibility and non-ideality of the mixed monolayers were examined by calculating the excess area as a function of composition, and negative deviations from ideality were observed, which suggest the existence of attractive interactions between iPMMA and PVPh. However, the π–A isotherms of mixed syndiotactic PMMA (sPMMA)/PVPh monolayers showed positive deviation from ideality, which might suggest that non-favorable interactions exist between sPMMA and PVPh. A isotherms of mixed atactic PMMA (aPMMA)/PVPh monolayers exhibited complicated excess area behavior. Both positive and negative deviations from ideality were observed at various surface pressures. These isotherm results of mixed polymers correlate approximately well with the miscibility of the corresponding mixtures in the bulk state. The formation of hydrogen bonding between PMMA and PVPh was substantiated in the bulk state by means of Fourier transform infrared (FTIR). Regardless of tacticity, an increase of hydrogen-bonded carbonyl fraction was observed.