Preparation of fluoroalkyl end-capped vinyltrimethoxysilane oligomer/micro-sized silica composites possessing superoleop

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ORIGINAL PAPER: SOL–GEL AND HYBRID MATERIALS WITH SURFACE MODIFICATION FOR APPLICATIONS

Preparation of fluoroalkyl end-capped vinyltrimethoxysilane oligomer/micro-sized silica composites possessing superoleophilic/ superhydrophobic characteristic: application to selective removal of aromatic compounds from aqueous methanol solution by using these composites Hideo Sawada1 Masaya Chiba1 Genta Honma1 Katsumi Yamashita1 Jun-ichi Suzuki2 ●







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Received: 31 March 2020 / Accepted: 18 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2–CHSi(OMe)3)n-RF; n = 2, 3; RF = fluoroalkyl group: RF-(VM)nRF] was found to undergo the sol–gel reaction in the presence of micro-sized silica particles under alkaline conditions to afford the corresponding fluorinated oligomer/micro-sized silica composites [RF-(VM-SiO3/2)n-RF/μ-SiO2]. The obtained composites were applied to the surface modification of glass to reveal a superoleophilic/superhydrophobic characteristic on the modified surface. In contrast, fluoroalkyl end-capped vinyltrimethoxysilane oligomer/silica nanocomposites [RF-(VM-SiO3/2)n-RF/n-SiO2], which were prepared in the presence of nanometer-sized silica particles under similar sol–gel reactions, provided an oleophobic/ superhydrophobic property on the surface. RF-(VM-SiO3/2)n-RF/μ-SiO2 composites were applied to the solid-phase extraction sorbent to isolate the transparent colorless oil from water-in-oil (W/O) emulsion. These composite powders were also applicable to the effective removal of traditional organic dyes, such as rhodamine B, acid red 289, and fluorescein from aqueous methanol solution. Of particular interest, it was demonstrated that RF-(VM-SiO3/2)n-RF/μ-SiO2 composites, of whose micro-sized silica gel is surface-functionalized with amino units, can exhibit a similar superoleophilic/superhydrophobic characteristic on the composite surface, giving the selective removal of fluorinated phenol-type aromatic compounds from aqueous methanol solutions, although the removal ability for the corresponding non-fluorinated ones was not observed at all under similar conditions. Graphical Abstract

* Hideo Sawada [email protected] 1

Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan

2

Kankyo Kogaku, Hirosaki 036-8093, Japan

Journal of Sol-Gel Science and Technology

Keywords Fluorinated oligomeric composite Micro-sized silica particle Superoleophilic/superhydrophobic property Separation of W/O emulsion Selective removal of fluorinated aromatic compounds ●







Highlights Fluoroalkyl end-capped oligomer/micro-sized silica composites possessing a superoleophilic/superhydrophobic characteristic were prepared. ● The obtained composites were applied to the separation of W/O emulsion to isolate the transparent colorless oil. ● Effective removal of organic dyes from aqueous methanol solutions was observed by