Reverse osmosis (RO) membranes composed of polyamides and cellulose acetates are used as separation layers in pure-water production. However, improving the separation performance and antifouling properties of RO membranes is necessary.
The term ‘fouling’ describes the adhesion of organic substances and bacteria to membrane surfaces. To resolve these problems, composite membranes comprising organic polymers and inorganic nanofillers have been developed. Recently, polyhedral oligomeric silsesquioxanes (POSSs), which are cage-shaped, subnanosized molecules exhibiting organic–inorganic hybrid structures, have been studied as nanofillers or building blocks for RO membranes. These reports, along with structural analyses and simulation studies, revealed that the incorporation of POSS components into RO membranes improved their water flux, NaCl rejection, chemical durability, and antifouling properties. This review describes recent research on the improvement of RO membranes by incorporating POSS components, including our previous related studies.