Abstract: Functionalized membranes are produced via grafting of polymer brushes to the membrane surface for use, e.g., in separation and purification of biomolecules. One or more initiators are attached to the membrane surface. A reactant substrate, such as a copper metal plate, is placed adjacent the membrane. A reaction medium is then provided in fluid contact with the membrane and the reactant substrate, the reaction medium including one or more monomers, one or more ligands, and one or more solvents. The polymer brushes are grown on the membrane via Cu(0)-mediated controlled radical polymerization involving the reactant substrate and the reaction medium. This reaction process uses fewer numbers and amounts of chemicals compared to other controlled radical polymerization reactions such as ATRP. The reaction can take place at room temperature, which is more energy efficient than other CRPs which occur at a much higher temperatures.