Structure of liquid films of an ordered foam confined in a narrow channel

A bamboo foam is the simplest case of an ordered foam confined in a narrow channel. It is made of a regular film distribution, arranged perpendicularly to the channel. Our work consists of studying the structural properties of several films taken in a drained foam. X-ray experiments highlighted the equality of the equilibrium thickness for each film within a foam. The same thickness was found as by measurements of disjoining pressure isotherms, proving as well that films of a bamboo foam behave like isolated ones. The refinement of X-ray data by a simple model of specular reflectivity showed a significant variation of the electronic distribution of the surfactant layer for a common black film forwarding from one equilibrium state to another. A discussion on the organization of the surfactant molecules to the gas/liquid interface and film is proposed.     

Characterization of Defects in PECVD-SiO2 Coatings on PET by Confocal Microscopy

Thin, transparent ceramic coatings on polymers are effective barriers against gas and vapor transmission. However, they always display some residual permeation, which can be attributed to defects. The main sources of these defects are dust particles on the polymer surface before deposition, and roughness of the polymer surface due to the presence of so-called antiblock particles. The transparency and extreme thinness of the films (d 50 nm) render the detection of defects virtually impossible by optical and even by electron microscopies. However, by using a technique based on reactive ion etching (RIE) in oxygen plasma, we are able to render defects visible, even by optical microscopy at relatively low magnification (100 ×). In the present article we present a confocal microscopy study, which has helped to better understand the effect of RIE at defect sites, as well as the origins of the defects in these coatings.