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. This focus review described the composite reverse osmosis membranes with optimal amounts of polyhedral oligomeric silsesquioxanes (POSS), which are cage-shaped, subnanosized molecules exhibiting organic–inorganic hybrid structures, showed improved water flux, NaCl rejection, antichlorine and antifouling properties, and mechanical strength.
