Dehydration-induced stable boroxine network as selective layer of anti-dye-deposition membranes

As a kind of functional heterocyclic polymer, the boroxine network could be facilely synthesized via dehydration reaction. However, due to the reversible nature of the dynamic covalent boroxine bond in water, it has rarely been used to fabricate membrane materials. Herein, we report the fabrication of selective layer of anti-dye-deposition membranes based on stable boroxine network for the first time. Functional polymers with pendant phenylboronic acid groups were dehydrated under mild conditions to form stable cross-linked boroxine network, which successfully acted as the selective layer of membranes. The pore size of selective layer could be well-tuned by changing the reaction conditions such as concentration, temperature, and vacuum degree. Compared with the original membrane, the composite membranes exhibit high separation performance towards organic molecules. In addition, the boroxine network demonstrated excellent chemical stability in water and could maintain stable permeation flux and retention rate after 30 days of operation. In particular, the modified membranes exhibited unexpected anti-fouling performance against organic dye clusters. After repeated anti-fouling cycles, the flux recovery rate of modified membranes was above 99.2%, highlighting the potential of the boroxine network in enhancing the anti-fouling performance of membrane.