Direct imaging of the structural transition and interconversion of macroporous bicontinuous diamond-surface structure

Abstract

Abstract The porous solids with bicontinuous structures have received significant attention due to their complex structure with unique physical functionalities. They are often obtained through structural transformation from lamellae or cylindrical precursors. However, the experimental verification of this relationship is challenging due to the short life-living of the structural intermediates and the soft nature of the assembled amphiphilic systems. Herein, we report the observation of the structural change of macroporous bicontinuous diamond-surface structure in the self-assembly of block copolymeric system with inorganic precursors in a mixture solvent of tetrahydrofuran (THF) and HCl aqueous solution. By controlling the addition amount of HCl/H2O, both the electrostatic interactions of the organic/inorganic precursor and the hydrolyzation and condensation rate of tetraethyl orthosilicate (TEOS) can be controlled. A structural transformation from bicontinuous diamond-surface to several intermediates between lamellar and bicontinuous structures has been observed with increasing the concentration of HCl. Our results show that the transition centers play an important role in the formation of the bicontinuous structure from the lamellae. Furthermore, we have proved the formation of interlamellar attachments (ILAs) and stalks as the intermediate phase. This study may bring new insights into the formation and the structural relationship of the bicontinuous porous solids and the corresponding relevant biological structures.