Hierarchically bimodal mesoporous silica fibers as building units for silica monolith with trimodal porous architecture

This work reports the controllable preparation of a unique kind of hierarchically mesoporous silica (HMS) fibers with bimodal porosities based on a simple TEOS/P123/HCl(aq.) templating system via the partitioned cooperative self-assembly (PCSA) process. Experimental results show that the formation of hierarchical mesostructures, especially the 2nd mode porous structure, depends on the interval time pertaining to the PCSA process. Synthetic conditions, including the interval time, temperature and stirring, are all found to be important in the evolution of fiber particle morphology. Moreover, such HMS fibers can be used as building units to prepare mesoporous silica monoliths with hierarchical trimodal pore systems via a simple gel-casting method, with additional (the 3rd modal) macropores originating from the packing of micron-sized HMS fibers. Such materials might further expand the application of both HMS fibers and HMS monoliths in various fields.