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Polymers 2018, 10(2), 116; https://doi.org/10.3390/polym10020116

A New Route for Preparation of Hydrophobic Silica Nanoparticles Using a Mixture of Poly(dimethylsiloxane) and Diethyl Carbonate

1
College of Science, Zhejiang University of Technology, Hangzhou 310023, China
2
Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine, 03164 Kyiv, Ukraine
3
College of Environment, Zhejiang University of Technology, Hangzhou 310023, China
*
Author to whom correspondence should be addressed.
Received: 18 January 2018 / Revised: 24 January 2018 / Accepted: 24 January 2018 / Published: 26 January 2018
(This article belongs to the Special Issue Siloxane-Based Polymers)
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Abstract

Organosilicon layers chemically anchored on silica surfaces show high carbon content, good thermal and chemical stability and find numerous applications as fillers in polymer systems, thickeners in dispersing media, and as the stationary phases and carriers in chromatography. Methyl-terminated poly(dimethylsiloxanes) (PDMSs) are typically considered to be inert and not suitable for surface modification because of the absence of readily hydrolyzable groups. Therefore, in this paper, we report a new approach for surface modification of silica (SiO2) nanoparticles with poly(dimethylsiloxanes) with different lengths of polymer chains (PDMS-20, PDMS-50, PDMS-100) in the presence of diethyl carbonate (DEC) as initiator of siloxane bond splitting. Infrared spectroscopy (IR), elemental analysis (CHN), transmission electron microscopy (TEM), atomic force microscopy (AFM), rotational viscosity and contact angle of wetting were employed for the characterization of the raw fumed silica and modified silica nanoparticles. Elemental analysis data revealed that the carbon content in the grafted layer is higher than 8 wt % for all modified silicas, but it decreases significantly after sample treatment in polar media for silicas which were modified using neat PDMS. The IR spectroscopy data indicated full involvement of free silanol groups in the chemisorption process at a relatively low temperature (220 °C) for all resulting samples. The contact angle studies confirmed hydrophobic surface properties of the obtained materials. The rheology results illustrated that fumed silica modified with mixtures of PDMS-x/DEC exhibited thixotropic behavior in industrial oil (I-40A), and exhibited a fully reversible nanostructure and shorter structure recovery time than nanosilicas modified with neat PDMS. The obtained results from AFM and TEM analysis revealed that the modification of fumed silica with mixtures of PDMS-20/DEC allows obtaining narrow particle size distribution with uniform dispersity and an average particle size of 15–17 nm. The fumed silica nanoparticles chemically modified with mixtures of PDMS-x/DEC have potential applications such as nanofillers of various polymeric systems, thickeners in dispersing media, and additives in coatings. View Full-Text
Keywords: poly(dimethylsiloxanes); surface modification; nanosilica; diethyl carbonate; carbon content; morphology; coatings; fillers poly(dimethylsiloxanes); surface modification; nanosilica; diethyl carbonate; carbon content; morphology; coatings; fillers
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Protsak, I.; Pakhlov, E.; Tertykh, V.; Le, Z.-C.; Dong, W. A New Route for Preparation of Hydrophobic Silica Nanoparticles Using a Mixture of Poly(dimethylsiloxane) and Diethyl Carbonate. Polymers 2018, 10, 116.

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