Thickness and Crystallinity Dependent Swelling of Poly(ethylene oxide)/Poly(methyl methacrylate) Blend Films

Polymer blends provide a diverse platform for adjusting polymer film properties. In this study, we probed the amorphous phase of thin film immiscible blends of poly(methyl methacrylate) (PMMA) and semi-crystalline poly(ethylene oxide) (PEO) and investigated how blend composition and film thickness influence film swelling under methyl ethyl ketone (MEK) vapor atmosphere. As the PEO content increases, the swelling decreases as the crystalline phase does not swell. Generally, the thinnest films (ca. 20 nm) swell more than thicker films (ca. 50 nm to 200 nm), but transitions in swelling behavior as a function of film thickness depend on the composition of the blend and morphology of the film. These investigations are relevant to applications that utilize blends of semicrystalline polymers, such as polymer electronics.