FLUCTUATION-STABILIZED SURFACE FREEZING OF CHAIN MOLECULES

We propose a fluctuation-based entropic scenario for the explanation o f surface freezing in alkanes and other liquids of chain molecules. Ou r model is based on the notion that strong fluctuations along the mole cular axis of uniaxially ordered stretched chains can exist in a solid monolayer on top of a liquid phase, and provide sufficient entropy to stabilize it against the formation of a bulk rotator phase. We show t hat the phenomenon can exist only in a restricted range of molecular w eights, and calculate the molecular weight dependences of the temperat ure range in which it is observed and of the correction to the surface tension.