ABSTRACT
In this paper, we show that a noncrystalline but ordered smectic-like phase exists above the bulk-melting temperature (T(m)) at poly(n-alkyl acrylates)-air interface. The surface ordered phase is one monolayer thick and undergoes a sharp transition from order to disorder 10 degrees C above T(m) for n=22. The presence of a surface phase that does not exist in the bulk has important implications in the design of thermally responsive adhesives.
ABSTRACT
Infrared-visible sum frequency generation spectroscopy (SFG) has been used to study the interface between poly(vinyl-N-octadecylcarbamate-co-vinyl acetate) (Comb) and deuterated or hydrogenated polystyrene (dPS or hPS) films. Strong methyl symmetric and Fermi resonance bands associated with the alkyl side chains of the Comb polymer are observed in the SFG spectra. In addition, for Comb/hPS spectra, symmetric and asymmetric vibration modes of phenyl groups are observed. The presence of asymmetric modes indicates the phenyl rings are tilted with respect to the interface normal.
