Miscibility of mixed monolayers of PBMA and its isomers at the air/water interface

The mixed monolayer behavior of poly(butyl methacrylate) (nPBMA) and its isomers (isoPBMA, secPBMA and tertPBMA) was investigated from the measurements of surface pressure–area per molecule (π–A) isotherms at two different temperatures. The miscibility and nonideality of the mixed monolayers were examined by calculating the excess area as a function of composition. Negative or close to zero deviations from ideality were observed mostly suggesting that the existence of miscibility between nPBMA and its isomers. Different temperature dependences of π–A isotherms of nPBMA and its isomers were observed likely because of predominantly enthalpic or entropic effect.