Isobaric relaxation phenomenon of mixed PMMA/PS-b-PEO monolayers at different temperatures

The objective of this research was to find out the effect of molecular weight of poly(methyl methacrylate) (PMMA) and temperature on the isobaric relaxation behaviors of mixed PMMA/poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) monolayers. Isobaric relaxation experiments of mixed monolayers of PMMA with different molecular weights and PS-b-PEO at the air/water interface were investigated at three different temperatures (10, 25, and 40°C). The PS-b-PEO monolayer was found to exhibit a fast relaxation curve (i.e., the surface area decreased significantly with increasing time). Addition of PMMA into PS-b-PEO slowed the relaxation behavior especially at the lowest experimental temperature (10°C). It was shown that the area relaxation process of mixed PMMA/PS-b-PEO monolayers could be well represented by a model considering the nucleation and growth mechanisms. The characteristic exponent x values were found to be almost temperature independent. The kx values were detected to decrease mostly as a result of temperature elevation regardless of pure or mixed monolayers.