摘要：

The static and dynamic properties of six different polymer monolayers at the air/water interface were examined with the surface quasi-elastic light scattering technique combined with the static Wilhelmy plate method. The polymers studied in order of increasing hydrophobicity were poly(ethylene oxide) (PEO), polytetrahydrofuran (PTHF), poly(vinyl acetate) (PVAc), poly(methyl acrylate) (PMA), poly(methyl methacrylate) (PMMA), and poly(tert-butyl methacrylate) (PtBMA). The isotherms of surface pressure versus surface area per unit mass can be classified into two types: PEO, PTHF, PVAc, and PMA exhibit the behavior of expanded-type monolayers and PMMA and PtBMA show that of condensed-type monolayers. The spectral data were analyzed in terms of the dispersion equation for capillary wave motion, and the dynamic longitudinal elasticity ε and the corresponding viscosity κ of the monolayers as a function of surface concentration were deduced. The static and dynamic elasticities were found to be the same over a majority of the concentration range. For the expanded-type monolayers, ε predominates over κ in determining the overall dynamic modulus ε*. For the condensed monolayers, PMMA and PtBMA, on the other hand, ε and κ contribute about equally to ε*. The absolute magnitudes of ε and κ increased with increasing hydrophobicity, with PEO the least and PtBMA the greatest.

展开