Dendrimer-like hybrid particles with tunable hierarchical pores

Abstract

Dendrimer-like silica particles with a center-radial dendritic framework and a synergistic hierarchical porosity have attracted much attention due to their unique open three-dimensional superstructures with high accessibility to the internal surface areas; however, the delicate regulation of the hierarchical porosity has been difficult to achieve up to now. Herein, a series of dendrimer-like amino-functionalized silica particles with tunable hierarchical pores (HPSNs-NH₂) were successfully fabricated by carefully regulating and optimizing the various experimental parameters in the ethyl ether emulsion systems via a one-pot sol–gel reaction. Interestingly, the simple adjustment of the stirring rate or reaction temperature was found to be an easy and effective route to achieve the controllable regulation towards center-radial large pore sizes from ca. 37–267 (148 ± 45) nm to ca. 8–119 (36 ± 21) nm for HPSNs-NH₂ with particle sizes of 300–700 nm and from ca. 9–157 (52 ± 28) nm to ca. 8–105 (30 ± 16) nm for HPSNs-NH₂ with particle sizes of 100–320 nm. To the best of our knowledge, this is the first successful regulation towards center-radial large pore sizes in such large ranges. The formation of HPSNs-NH₂ may be attributed to the complex cross-coupling of two processes: the dynamic diffusion of ethyl ether molecules and the self-assembly of partially hydrolyzed TEOS species and CTAB molecules at the dynamic ethyl ether–water interface of uniform small quasi-emulsion droplets. Thus, these results regarding the elaborate regulation of center-radial large pores and particle sizes not only help us better understand the complicated self-assembly at the dynamic oil–water interface, but also provide a unique and ideal platform as carriers or supports for adsorption, separation, catalysis, biomedicine, and sensor.