Abstract
In this study, the phase transitions of mono-disperse poly(ethylene oxide), PEOn, thin films with thickness less than 1 μm were investigated as a function of sample mass which was proportional to sample thickness. The solvent cast PEOn thin films consisted of the crystal lamella oriented to in-plane and out of plane directions showed several melting peaks on DSC heating curves. However PEOn thin films prepared by slow cooling from the molten state showed branch-like crystal lamella with homogenous thickness and a single melting peak on DSC heating curves. The crystallization process of PEOn on cooling was restricted strongly with the decrease of sample mass. The crystallization exothermic peak became broader and smaller with the decrease of sample mass, and was varnished for PEO thin film less than 200 nm thickness.
