A facile route to the preparation of mixed matrix polyvinylidene fluoride membranes with in-situ generated polyethyleneimine particles

The development of mixed matrix polymeric membranes with embedded functional particles/nanomaterials has been an active area of research during the last two decades. Such membranes are being designed to carry out multiple functions (e.g. retention, sorption and catalysis) with improved properties and performance over those of commercial membranes. Polymeric particles could provide greater flexibility for the preparation of mixed matrix membranes with improved particle–matrix compatibility, particle loading, flux and permselectivity. In this article, we describe a facile and simple route to the preparation of mixed matrix polyvinylidene fluoride (PVDF) membranes embedded with branched polyethylenimine (PEI) particles. The critical step of our novel methodology is the in-situ generation of crosslinked PEI micro/nanoparticles (with diameters ranging from 400 nm to 3 μm) in the membrane casting solution using epichlorohydrin as crosslinker. This eliminates the need to utilize inverse emulsion polymerization techniques to synthesize PEI particles prior to the membrane casting. Using non-solvent induced phase separation (NIPS), we successfully prepared mixed matrix PVDF membranes with uniform particle distribution and PEI particle loadings ranging from 27 to 48 wt%. Our novel membrane preparation route exhibits many advantages including simplicity, scalability and versatility. Preliminary experiments show that our new mixed matrix PVDF membranes with embedded PEI particles can serve as weak-base membrane absorbers for proteins such as bovine serum albumin.