Determination of the Thickness of Interfacial Voids in a Spherical Nanoparticles - Polymer Membrane: Fundamental Insight from the Gas Permeation Modeling

Abstract

In this work, a new approach is proposed to determine the thickness of interfacial voids in impermeable spherical nanoparticles-containing mixed matrix membranes (SP-MMMs) based on the gas permeation data. The interfacial void thickness, lv, between SPs and polymer matrix is firstly obtained as an adjustable parameter by fitting the modified Maxwell model to the experimental gas permeability data reported in the literature. It is shown that the value of lv parameter is independent of the nature of gas molecules and mathematically related to the strength of SP/matrix interfacial interactions. Then, for the first time in this paper, a universal relationship is established between the SPs/polymer interfacial void thickness and the interfacial interactions at the SPs/polymer interface, which is described by the Flory–Huggins interaction parameter, χ. Finally, the gas permeability of SP-MMMs is predicted using the values of lv parameter, diameter and volume fraction of SPs as well as the gas permeability of polymer matrix. Moreover, according to the obtained relationship, the interfacial void thickness in SP-polymer composites can be directly calculated for a wide range of interaction parameter values.