Preparation of bridged polysilsesquioxane-based membranes containing 1,2,3-triazole moieties for water desalination

To develop reverse osmosis membranes with high water permeance, new organically bridged trialkoxysilanes, 1,4-bis (triethoxysilylmethyl)1,2,3-triazole (BTES-MAz) and 3-methyl-1,4-bis(triethoxysilylmethyl)-1,2,3-triazol-3-ium iodide (BTES-MAz-MeI), containing 1,2,3-triazole moieties as hydrophilic and rigid units were synthesized. The monomers were polymerized via sol–gel reactions to yield films and membranes. Pencil hardness tests and water contact angle measurements of the BTES-MAz film surface were performed to show that the surface of this film was softer and more hydrophobic than that of film prepared from bis(triethoxysilyl)ethane (BTES-E1). The water separation properties of the BTES-MAz-derived membrane were investigated using a 2000 p.p.m. NaCl aqueous solution, and the membrane exhibited a water permeance of 3.7–5.4×10−13 m3/m2 Pa s and 95–96% NaCl rejection. The separation of neutral solutes such as 2-propanol, glucose and maltose from water using the BTES-MAz membrane was also examined, and the results indicated that the BTES-MAz membrane had a slightly larger pore size than the BTES-E1 membrane, likely ascribable to the introduction of the rigid 1,2,3-triazole units. To improve the hydrophilicity of the membrane, the methyltriazolium iodide BTES-MAz-MeI was synthesized via the iodomethylation of BTES-MAz, and its application in separation membranes was investigated. Polymer Journal (2017) 49, 401–406; doi:10.1038/pj.2016.128; published online 25 January 2017