Three characterization techniques coupled with adsorption for studying the nanoporosity of supported films and membranes

Abstract

Three characterization techniques are described for studying the open nanoporosity, i.e. the open free volume, the microporosity, the mesoporosity and the thickness variation of thin deposited films during gas adsorption and condensation. They are all based on the coupling of the sorption of a probe gaseous molecule at room temperature and a physical characterization tool of thin deposited films: the quartz crystal microbalance, ellipsometry and X-ray reflectometry, giving the mass uptake, the refractive index variation and the electronic density variation, respectively, of the film due to the adsorbate intrusion inside the open free volume and pores. The film thickness evolution during the sorption can also be followed by the two last techniques. These techniques are complementary because each one can bring specific properties and can validate the results of another one. Both static and dynamic measurements can be carried out to characterize the porosity, the contraction or the swelling of the film and the penetration rate of the gas.