The preparation of hierarchical zeolites usually involves hard or soft templates and multiple synthesis steps, which often prohibit their industrial uses. One way to overcome these issues is to build hierarchical zeolites using repetitive branching, where the intrinsic growth patterns of zeolites, instead of porogenic templates, are utilized. This paper expands on an earlier report to unravel the sequence of events leading to this repetitive branching process for the framework type MFI zeolite structure using small‐angle X‐ray scattering and transmission electron microscopy. Moreover, adsorption and transport properties of the hierarchical zeolite are probed using 2,2‐dimethylbutane, n‐hexane, and n‐nonane.

Oxygen homeostasis is important in the regulation of biological function. Disease progression can be monitored by measuring oxygen levels, thus producing information for the design of therapeutic treatments. Non-invasive measurements of tissue oxygenation require the development of tools with minimal adverse effects and facile detection of features of interest. Fluorine magnetic resonance imaging (19F-MRI) exploits the intrinsic properties of perfluorocarbon (PFC) liquids for anatomical imaging, cell tracking, and oxygen sensing. However, the highly hydrophobic and lipophobic properties of perfluorocarbons require the formation of emulsions for biological studies. Though, stabilizing these emulsions has been challenging. To enhance the stability and biological loading of perfluorocarbons, one option is to incorporate perfluorocarbon liquids into the internal space of biocompatible mesoporous silica nanoparticles. Here, we developed perfluorocarbon-loaded ultraporous mesostructured silica nanoparticles (PERFUMNs) as 19F-MRI detectable oxygen sensing probes. Ultraporous mesostructured nanoparticles (UMNs) have large internal cavities (average = 1.76 cm3 g−1), facilitating an average 17% loading efficiency of PFCs, meeting the threshold fluorine concentrations needed for imaging studies. Perfluoro-15-crown-5-ether PERFUMNs have the highest equivalent nuclei per PFC molecule, and a spin-lattice (T1) relaxation-based oxygen sensitivity of 0.0032 mmHg−1 s−1 at 16.4 T (657 MHz). The option of loading PFCs after synthesizing UMNs, rather than the more traditional in situ core-shell syntheses, allows for use of a broad range of PFC liquids from a single material. The biocompatible and tunable chemistry of UMNs combined with the intrinsic properties of PFCs makes PERFUMNs a MRI sensor with potential for anatomical imaging, cell tracking, and metabolic spectroscopy with improved stability.

M esoporous silica materials find use in many applications such as catalysis, separations, drug delivery, and gas adsorption wherein a large pore volume is desirable. 1−4 High pore volumes can be achieved by swelling traditional surfactant templates, 5−8 by employing larger templates such as block copolymers 9,10 or sacrificial nanoparticles, 11,12 or through interface-directed syntheses. 13−20 For example, Stucky and coworkers demonstrated structural control over silica materials at two size scales by utilizing phase boundaries at the micelle level and at a bulk oil−water interface. 13 Oil−water interfaces were also used in the biphasic stratification synthesis of dendritic mesoporous silicas. 19 Further, solid−liquid interfaces between 3DOM carbon materials and water resulted in uniform silica nanoparticles with large pores. 20 Despite novel structures and pore swelling strategies, pore volumes of mesoporous silica nanoparticles have seldom topped 2.0 cm 3 g −1 . 21−23 In addition, swollen or hollow structures can suffer from other disadvantages. Some literature describes small micro-or mesopores on the shell portion of a particle, 14,24 and many schemes result in thin silica walls, 25,26 all of which are prone to breakage and aggregation.Herein, we report the development of a new mesoporous silica nanoparticle structure with extremely high pore volume and an open pore structure. These nanoparticles, which are formed from combinations of surfactant swelling strategies, stirring, and sonication, demonstrate pore volumes of up to 4.5 cm 3 g −1 while maintaining the high surface areas of traditional mesoporous silica (>1000 m 2 g −1 ). In addition, these structures demonstrate thermal stability and mechanical sturdiness. We propose that this new structure is formed through micellar aggregation during silica condensation.These ultraporous mesostructured nanoparticles (UMN) were synthesized with cetyltrimethylammonium bromide (CTAB) as a surfactant, dimethylhexadecylamine (DMHA) as a cosurfactant, and decane as an oil phase (exact combinations are shown in Table 1). Prior to silica condensation from tetraethylorthosilicate (TEOS), CTAB, DMHA, and decane mixtures were stirred and then sonicated for 90 min. The prepared suspension was equilibrated at 50 °C. After TEOS condensation, the synthesized material was dialyzed and centrifuged at 66 000 × g multiple times for purification.The textural properties of UMN are shown in Figure 1, Table 1, and Supporting Information Table S1 and Figures S1−S3. The difference in transmission electron microscopy (TEM) mass contrast between the center and edges of each particle suggests either a hollow or lacy interior silica network (Figure 1a). Image analysis of UMN-3, the structure with the highest pore volume, revealed average particle diameters of 71.3 ± 13.4

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