(376ab) Star Polymers As a New Building Block for the Fabrication of Reverse Osmosis and Nanofiltration Membranes

Star polymers with a globular structure are attractive materials since the chemistry of their core and arms can be tailored for the suitable applications. In this work, star polymers with the high density of amine groups were synthesized via atomic transfer radical polymerization (ATRP), followed by amine end-functionalization for their application to the membranes for water treatment and desalination. First, the well-defined poly (methyl acrylate) (PMA) star polymers consisting of PMA linear polymer arms and a cross-linked poly (ethylene glycol dimethacrylate) core were synthesized via ATRP based on an arm-first approach. The methyl oxy groups of PMA arm polymers were then substituted with hydrazine groups to produce the amine-functionalized poly (acryloyl hydrazide) (PAH) star polymer. The synthesized PAH star polymer was employed to fabricate thin film composite membranes for water desalination via the interfacial polymerization (IP) of the star polymer and trimesoyl chloride. High density reactive functional groups and compact globular structure of the star polymer enable to form a unique selective layer structure, consisting of a highly cross-linked, selective topmost layer on a less dense, permeable sublayer containing the large number of interstitial voids. Importantly, the star polymer-assembled membrane exhibited a significant improvement both in the permeselectivity and antifouling performance compared to commercial membranes. In addition, reverse osmosis and nanofiltration grade performance can be achieved by simply adjusting the IP process parameters, which is not feasible with conventional monomers, demonstrating the excellent versatility of the star polymer.