Polyurethane-based separation membranes: A review on fabrication techniques, applications, and future prospectives

Nowadays, reaching a membrane with good mechanical/thermal properties, biocompatibility, and industrial application is a big challenge in science and technology. Polyurethane (PU) has been known as a polymer with excellent and distinct properties, such as biodegradability, biocompatibility, and also exclusive chemistry can be considered an important part of a membrane, especially in polymeric ones. Therefore, this review aims to introduce polyurethane and urea bond properties, structures, and chemistry and then review studies related to the polymeric separation of membranes. It is expected that the versatility of polyurethane in various states from flexible to rigid and from compact to foamed, which can be produced easily through selecting various starting materials, makes it a suitable target to be used in various membrane applications. This review also highlights the synthesis methods of polyurethane and related membranes and considers the role of chain extenders and some fillers in changing the properties of polyurethane polymeric membranes in various categories such as exchange membranes, distillation membranes, thin-film composite membranes, gas separation membranes, and ultrafiltration, nanofiltration and microfiltration membranes. Other synthesized polyurethane-based membranes are introduced briefly and some prospective about the future of polyurethane is mentioned in the end.