posted on 2020-03-13, 19:39authored byHeng Yu, Qin Wang, Yongliang Zhao, Haitao Wang
Functional porous
materials show extensive applications in the
environment, biology, aerospace, and so on. In this work, the generation
of silica foams and functionalization of pore surface were simultaneously
realized through an interfacial sol–gel reaction within high
internal phase emulsion (HIPE) microreactors, where a hyperbranched
polyethoxysiloxane (PEOS) was used as the sole stabilizer for the
HIPEs. With various functional substances containing amino, epoxy,
and carboxyl groups initially dissolved in the aqueous phase of HIPEs,
these functional groups could be grafted onto the pore surface in
the process of forming silica foams. Amino-functionalized silica foam
showed fast adsorption of sunset yellow, and the adsorption capacity
could reach as high as 1213.13 mg/g. Sodium polyacrylate-modified
silica foam exhibited good adsorption capacity of cationic dyes and
metal ions, e.g., 280.11 mg/g to methylene and 226.24 mg/g to Cu(II).
Epoxy-functionalized silica foam particles were confirmed with a pronounced
activity at the oil/water interface due to their Janus-like surface,
which could be used as Pickering stabilizer. This HIPE-based synthesis
strategy for silica foams shows promising future in adsorption, emulsion
stabilization, and compatibilization.