Surface Engineering of Polymer Membranes: An Introduction

Abstract

Polymeric separation membranes develop rapidly and have been applied in many fields. Filtration with polymer membranes covers the separation of industrial chemicals, purification of laboratory products and treatment of drinking water. For all these processes, the performance limits are clearly determined by the membrane itself. Flux and rejection of a membrane process such as microfiltration or ultrafiltration are mainly influenced by size exclusion. Nevertheless, surface properties of the membrane also play a crucial role. It is because membrane fouling, induced by adsorption of matter onto the membrane surface or deposition into the pores, is mainly controlled by the surface properties. For example, a hydrophobic membrane surface is apt to cause adsorption of protein or other solutes due to hydrophobic interactions. As is well known, membrane fouling will decline the flux and deteriorate the selectivity. Meanwhile, the products must meet the ever stricter environmental or safety standards. A membrane separation system should consist of a membrane with stable and reliable performance. Therefore, the first objective of polymer membrane surface engineering is to enhance the surface properties of the membrane by modulating its surface chemistry and physics, and hence improve the performance of the membrane.