Key Parameters to Tailor Hollow Silica Nanospheres for a Type I Porous Liquid Synthesis: Optimized Structure and Accessibility

Abstract

Based on silica hollow nanospheres grafted with an ionic shell, silica-based type I porous liquids remain poorly exploited, despite their huge versatility. We propose here to explore the main synthesis step of these promising materials with a thorough characterization approach to evaluate their structural and porous properties. Modifying the main synthesis parameter, the mechanism of the spheres’ formation is clarified and shows that the calcination temperature, the surfactant concentration as well as the micelle swelling agent concentration allow tuning not only the size of the nanospheres and internal cavities, but also the silica shell microporosity and, therefore, the accessibility of the internal cavities. This study highlights the key parameters of hollow silica nanospheres, which are at the basis of type I porous liquids synthesis with optimized structural and porous properties.

Porous liquids – the future is looking emptier

“…As with the type II porous liquids described above, this strategy was subsequently applied to other systems. For example, silica nanoparticles functionalised with different corona and canopy species were reported as additional examples of type I porous liquids; 31,32 nanosized silicalite-1 zeolite particles were subjected to a surface sol–gel process to form particles decorated with organosilanes (OS) and poly(ethylene glycol) (PEG) tails; 33 hollow silica nanorods were covalently functionalised with an OS canopy before electrostatic grafting of a polymer surfactant to afford a solvent-free mesoporous liquid; 34 and metal–organic frameworks (MOFs) were surface-modified with OS and oligomeric species via covalent bonding to form a porous fluid at room temperature. 35,36 In addition, similar approaches were later demonstrated with hollow carbon spheres (HCS) decorated with polymeric ionic liquids by exploiting the electrostatic interaction between the two species (Fig.…”

Practical considerations in the design and use of porous liquids

“…Thus, the cavity accessibility can be adjusted. 76 However, the lack of sufficient grafting sites on the surface limits the surface modifications. 77,78 There are different approaches to increase the grafting sites.…”

Lead Extraction in a Functionalized and Permeable Silica-Based Porous Liquid

“…In this study, a silica-based PL was used as a solvent-free extracting agent for the extraction of lead from an aqueous solution. As illustrated in Figure 1, we followed the synthesis methodology proposed by Zhang et al 2 and applied an optimized characterization 6 to synthesize PLs based on silica hollow spheres (HSs) grafted with organic coronas. The PL was primarily functionalized with thiols to enhance lead capture in the silica shells.…”