A surface light scattering study of a poly(ethylene oxide)-polystyrene block copolymer at the air-water and heptane-water interfaces

Abstract

Spread films of a poly(ethylene oxide)-polystyrene diblock copolymer were studied at the h a t e r and heptanewater interfaces by using the Wilhelmy plate technique and surface quasi-elastic light scattering (SLS) from capillary waves. At the air-water interface, the dynamic f i l m viscoelastic parameters, Le., surface pressure, surface dilational elasticity and viscosity, and transverse viscosity, were deduced from the SLS measurements. The static surface tension and dilational elasticity were compared to their dynamic counterparts from SLS. At the heptanewater interface, the dynamic surface pressure and transverse viscosity were evaluated, and the latter was found to be zero for the whole surface concentration range. Some speculations about possible chain conformations of the copolymer at the two interfaces are offered.

Density Estimation of Liquid/Liquid Interfacial Regions Using a Quasi-Elastic Laser Scattering Method

“…Some researchers have reported the surface viscosity as determined from the width of the capillary wave spectra. 26,35,45,46 In the present study, however, the instrumental function was undetermined because of the transmitting optical configuration employed for the observation of the interface, and the width could not be used for the analysis. Regarding the reported results, the interfacial viscosity was difficult to determine even for liquid surfaces, and Langevin 26 has reported that a highly viscous surface region does not exist on the water surface.…”

Polymer Brushes

“…have performed similar Wilhelmy-plate studies in conjunction with surface light scattering from capillary waves at air-water and oil-water interfaces at which short (M, = 4135) polyethylene oxide-polystyrene (PEO-PS) diblock copolymers were adsorbed (55). They found excellent agreement between the two methods of extracting ~( u ) .…”

“…K. ALmdal, K. Koppi, F. S. Bates, K. Monensen, unpublished results. 55. G. Hadziioannou and A. Skoulios, Macromolecules 15, 258 (1982).…”

Lipid Lateral Diffusion in Dilauroylphosphatidylcholine/Cholesterol Mixed Monolayers at the Air/Water Interface

“…Water used here was the house-deionized, further purified by a Milli-Q system with the initial resistivity of greater than 17 MΩ. The monolayer mass density for all measurements was varied by the successive addition method at a controlled room temperature (296.0 ± 0.5 K), under the assumption that spread components form insoluble monolayers without any desorption from the surface into the subphase . In our experience with monolayers in fluid state, there is no dependence of surface pressure and diffusion coefficient on the film preparation method. , It is possible however that phase domain size and morphology for the fluid monolayers at an apparent equilibrium state can vary with the film preparation method.…”