Conceptual Design of Large Surface Area Porous Polymeric Hybrid Media Based on Polyhedral Oligomeric Silsesquioxane Precursors: Preparation, Tailoring of Porous Properties, and Internal Surface Functionalization

Abstract

We report on the preparation of hybrid, organic–inorganic porous materials derived from polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) via a single-step molding process. The monolithic, large surface area materials are studied with a particular focus on morphology and porous properties. Radical vinyl polymerization of the nanometer-sized POSS building blocks is therefore utilized via a thermally initiated route and in porogenic diluents such as tetrahydrofuran and polyethylene glycols of varying composition. Careful choice of these porogenic solvents and proper choice of initiator concentration lead to highly porous monolithic building entities which show a rigid, 3D-adhered, porous structure, macroscopically adapting the shape of a given mold. The described materials reflect Brunauer–Emmett–Teller (BET) surface areas of 700 m2/g or more and maximum tunable mesopore volumes of up to 2 cm3/g. Experimental investigations demonstrate the option to tailor nanoporosity and macroporosity in the single-step free-radical polymerization process. While studies on the influence of the used porogenic solvents reveal tuneability of pore sizes due to the unique pore formation process, tailored existence of residual vinyl groups allows facile postpolymerization modification of the highly porous, large surface area hybrid materials exploited via thiol–ene “click” chemistry. Our developed, simply realizable preparation process explores a new route to derive porous organic–inorganic hybrid adsorbents for a wide variety of applications such as extraction, separation science, and catalysis.

In‐process thermochemical analysis of in situ poly(ethylene glycol methacrylate‐co‐glycidyl methacrylate) monolithic adsorbent synthesis

“…Polymethacrylate monoliths are synthesized via the free‐radical copolymerization of a crosslinker and functional methacrylate‐based monomers that is initiated either thermally or by radiation . The thermal initiation approach is commonly used, as it is cheap and primarily requires the use of an isothermal water bath . The synthesis process includes various steps of thermomolecular mechanisms involving the monomers and the initiator.…”

“…[11][12][13] The thermal initiation approach is commonly used, as it is cheap and primarily requires the use of an isothermal water bath. 14,15 The synthesis process includes various steps of thermomolecular mechanisms involving the monomers and the initiator. These steps are: 1.…”

Microporous inorganic/organic hybrids via oxysilylation of a cubic symmetry nanobuilding block [(HMe₂SiOSiO_1.5)₈] with R<i>_x</i>Si(OEt)_4&minus;<i>_x</i>

“…Silsesquioxane based high SSA materials have been synthesized by FriedelCrafts, 43)45) cross-coupling, 41),46) 48) thiol-ene, 49) radical polymerization, 50) polyesters/polyimides, 51),52) and hydrosilylation. 42)53) The best of these materials made by FriedelCrafts reaction was reported by Chaikittisilp et al, in which they have achieved 2500 m 2 /g.…”

Alkanethiol‐functionalized organosilicon monoliths for nano‐reversed‐phase liquid chromatography

“…Polyhedral oligomeric silsesquioxane (POSS) based monoliths have recently been proposed as a new hybrid monolith family in RP chromatography applications carried out in nano/micro‐liquid chromatography systems . These monoliths with high cross‐linking density mostly exhibit retention‐independent chromatographic separation efficiency and also high mechanical and chemical resistance.…”