Probing in-situ polymeric particle growth in mixed matrix membranes using ultra-small angle neutron scattering

Abstract

Recent advances in the prepn. of mixed matrix membranes with embedded polymeric particles are providing new opportunities to develop the next generation of multifunctional membranes for sustainable chem., engineering, and materials (SusChEM). One such advance combines the durability of polyvinylidene fluoride with the diverse functionality of hydrophilic polymers. Essential to the prepn. of these membranes is the in-situ synthesis of microgel particles in the membrane casting soln. The fouling resistance, stability, and facile functionalization (e.g., metal binding) of these membranes have been well documented; however, understanding the structure-function relationship has proven challenging due to their optical opacity and lack of x-ray scattering contrast. To address this challenge, we developed a new method using ultra-small angle neutron scattering (USANS) to measure microstructure formation in membrane casting solns. Previously, USANS has been limited to equilibrated systems. Here, we use USANS to measure transient structural changes during microgel particle growth. This method will enable not only in-depth structural anal. of membrane casting solns., but also the study of transient microstructure in multicomponent polymer systems in general.