Molecular weight effect of PMMA on its miscibility with PS‐ b ‐PEO at the air/water interface

The mixed monolayer behavior of poly(methyl methacrylate) (PMMA) with different molecular weights and polystyrene‐ block ‐polyethylene oxide (PS‐ b ‐PEO) was investigated from the measurements of surface pressure–area per molecule (π‐A) isotherms at three different temperatures (10°C, 25°C, and 40°C). The miscibility and nonideality of the mixed monolayers were examined by calculating the excess surface area as a function of composition. The molecular weight of PMMA was demonstrated to have a major effect on its miscibility with PS‐ b ‐PEO. Negative or close to zero deviations from ideality of surface areas were observed for PMMA with the lowest molecular weight (12,000 g/mole). Mostly positive deviations were detected in mixed PMMA/PS‐ b ‐PEO monolayers with higher molecular weights of PMMA. Because of probable mushroom‐to‐brush transition effect, the miscibility between PMMA and PS‐ b ‐PEO was found to be the best at 25°C among the experimental temperatures. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012