One-dimensional periodic mesoporous organosilica helical nanotubes with amphiphilic properties for the removal of contaminants from water†
In this work, we report one new class of one-dimensional highly uniform periodic mesoporous organosilica (PMO) helical nanotubes with a unique amphiphilic framework and perpendicular mesochannels in walls through a simple, efficient and controllable one-step strategy. The chiral mesoporous silica (CMS) nanorods were used as hard templates. The evolution of the nanotube structure involved a process of organosilane-directed growth-induced etching, in which the growth of the external PMO wall promoted the dissolution of internal CMS nanorods, and the dissolved silicate species transformed into the external PMO wall by co-condensation with hydrolyzed organosilane oligomers. Moreover, the helical morphology was retained completely in the process of structural evolution. In addition, PMO helical nanotubes with different aspect ratios, wall thicknesses and curvatures as well as chemical compositions could be easily prepared via this strategy. Furthermore, the PMO helical nanotubes exhibited good amphiphilicity and can be used as a particle emulsifier for fabricating Pickering emulsions with different morphologies in various systems. Most importantly, the PMO helical nanotubes showed outstanding performance in the removal of hydrophobic contaminants from water, whose sorption capacity (1800–3000 mg g−1) was much higher than those of mesosilica nanotubes and conventional MCM-41, and even comparable to those of some sponges.