Plasma Treatment of Polymeric Membranes

In the past several decades, processes that rely on the use of polymeric membranes have received considerable attention for the important role they play in biological and industrial fields. Surface properties are critical to membrane applications, yet a number of polymers that are both suitable for membrane manufacturing and possess necessary surface properties is often limited. Thus, modification of membrane surfaces is often used to fulfil diverse requirements. Nonequilibrium plasma treatment is an efficient method to tailor/adapt surface morphology and chemical structure of polymers without changing the bulk properties of the treated material. Plasma conditions play a significant role in controlling physico-chemical properties, and can be used to selectively modify surface energy, roughness, and biocompatibility of the polymer, as well as introduce new surface functional groups, e.g. carboxyl, hydroxyl, or amino functionalities, onto the surface of the membrane. This chapter will review the use of nonequilibrium plasma surface treatment for modification of polymeric membranes. First, the key interactions between physical and chemical effects of cold plasma and material surfaces will be briefly introduced. Then, specific examples for the usage of plasma to improve biological activities and mitigate biofouling properties of membranes will be discussed. Finally, plasma-induced grafting on membranes and plasma modification using several of the most common nonpolymerizable gases will be reviewed.