Controllable Construction Of Heterogeneous Membrane Surfaces And Synergistic Intensification Of Multiple Antifouling Mechanisms

The intensification of the antifouling properties of membrane surface is one of the main strategies to pursue high-performance membranes. The microstructure and antifouling mechanisms of membrane surfaces are identified as the two key scientific issues that determine the antifouling performance. Based on the platform technique of surface segregation, surface grafting and biomimetic mineralization, this study establishes the methods for the controllable construction of heterogeneous structure on membrane surfaces, and puts forward the theories for the synergistic intensification of multiple antifouling mechanisms of membrane surfaces. This study is in pursuit of offering academic thoughts to the materials design and preparation of antifouling membranes for water treatment applications. The details are summarized as follows:Construction of the heterogeneous structure of membrane surfaces and intensification of fouling release mechanism:(i) Based on the phenomenon and principle of surface segregation, both hydrophilic segments and low surface energy fluorine-containing segments were decorated on membrane surfaces to construct heterogeneous structure. The forced surface segregation of fluorine-containing segments on membrane surfaces favored the formation of low surface energy barrier to decrease the interaction between protein and membrane surfaces, which intensified the fouling release mechanism;(ii) Based on the principles and methods of surface grafting, both hydrophilic groups and low surface energy perfluoroalkyl groups were tailored on membrane surfaces to construct heterogeneous structure. The introduction of perfluoroalkyl groups helped to build low surface energy barrier to decrease the interaction between oil, protein or polysaccharide and membrane surfaces, which intensified the fouling release mechanism.Construction of the heterogeneous structure of membrane surfaces and synergistic intensification of multiple antifouling mechanisms:(i) Based on the phenomenon and principle of surface segregation, both hydrophilic segments and low surface energy siloxane-containing segments were decorated on membrane surfaces to construct heterogeneous structure. The forced surface segregation of siloxane-containing segments on membrane surfaces favored the formation of low surface energy barrier to decrease the interaction between biofoulants and membrane surfaces. The free surface segregation of hydrophilic segments favored the formation of hydration layer barrier to avoid the direct contact between biofoulants and membrane surfaces. Both effects synergistically intensified the multiple antifouling mechanisms;(ii) Based on the phenomenon and principle of surface segregation, the coordination chemistry-enabled synergistic surface segregation strategy was put forward to construct both hydrophilic segments, inorganic nanoparticles and low surface energy fluorine-containing segments on membrane surfaces for heterogeneous structure. The forced surface segregation of fluorine-containing segments on membrane surfaces imparted low surface energy barrier to decrease the interaction between oil and membrane surfaces. The synergistic surface segregation of hydrophilic segments and inorganic nanoparticles imparted robust hydration layer barrier to avoid the direct contact between oil and membrane surfaces. Both effects synergistically intensified the multiple antifouling mechanisms;(iii) Based on the phenomenon and principle of biomineralization, the biomimetic mineralization strategy was utilized to generated hydrophilic nanoparticles and low surface energy fluorine-containing groups on membrane surfaces for heterogeneous structure. The in situ mineralization of TiO2 nanoparticles endowed membrane surfaces with hydration layer barrier to avoid the direct contact between oil and membrane surfaces. The introduction of fluorine-containing groups endowed membrane surfaces with low surface energy barrier to decrease the interaction between oil and membrane surfaces. Both effects synergistically intensified the multiple antifouling mechanisms.