Mixed matrix membranes are a type of membrane that consists of filler particles dispersed in a polymer matrix. In theory, these membranes should have excellent gas separation properties. However, the adhesion between the filler and polymer is often defective, resulting in non-selective voids, pore blockage, or even densification of the polymer in the region near the filler. Defects near the filler/polymer interface can have a negative effect on transport properties of the membrane resulting in decreased permeability and selectivity.

The current invention describes a method for surface modification of metal-organic framework filler particles to improve their compatibility with the polymer matrix resulting in increased interface interaction. The surface modified membranes contain fewer defects at the filler/polymer interface resulting in improved gas separation properties.