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Open AccessArticle

Nanostructured Polymethylsiloxane/Fumed Silica Blends

1
College of Environment, Zhejiang University of Technology, Hangzhou 310014, China
2
College of Science, Zhejiang University of Technology, Hangzhou 310023, China
3
Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine, Kyiv 03164, Ukraine
4
Department of Chemical & Biomolecular Engineering, University of Akron, Akron, OH 44325, USA
*
Author to whom correspondence should be addressed.
Materials 2019, 12(15), 2409; https://doi.org/10.3390/ma12152409
Received: 27 June 2019 / Revised: 25 July 2019 / Accepted: 26 July 2019 / Published: 28 July 2019
(This article belongs to the Section Structure Analysis and Characterization)
Polymethylsiloxane (PMS) and fumed silica, alone and in a blended form (1:1 w/w), differently pretreated, hydrated, and treated again, were studied using TEM and SEM, nitrogen adsorption–desorption, 1H MAS and 29Si CP/MAS NMR spectroscopy, infrared spectroscopy, and methods of quantum chemistry. Analysis of the effects of adding water (0–0.5 g of water per gram of solids) to the blends while they are undergoing different mechanical treatment (stirring with weak (~1–2 kg/cm2) and strong (~20 kg/cm2) loading) show that both dry and wetted PMS (as a soft material) can be grafted onto a silica surface, even with weak mechanical loading, and enhanced mechanical loading leads to enhanced homogenization of the blends. The main evidence of this effect is strong nonadditive changes in the textural characteristics, which are 2–3 times smaller than additive those expected. All PMS/nanosilica blends, demonstrating a good distribution of nanosilica nanoparticles and their small aggregates in the polymer matrix (according to TEM and SEM images), are rather meso/microporous, with the main pore-size distribution peaks at R > 10 nm in radius and average <RV> values of 18–25 nm. The contributions of nanopores (R < 1 nm), mesopores (1 nm < R < 25 nm), and macropores (25 nm < R < 100 nm), which are of importance for studied medical sorbents and drug carriers, depend strongly on the types of the materials and treatments, as well the amounts of water added. The developed technique (based on small additions of water and controlled mechanical loading) allows one to significantly change the morphological and textural characteristics of fumed silica (hydrocompaction), PMS (drying–wetting–drying), and PMS/A-300 blends (wetting–drying under mechanical loading), which is of importance from a practical point of view. View Full-Text
Keywords: polymethylsiloxane/nanosilica blends; hydration effect; mechanical loading effect; textural characteristics; interfacial layer structure polymethylsiloxane/nanosilica blends; hydration effect; mechanical loading effect; textural characteristics; interfacial layer structure
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MDPI and ACS Style

Protsak, I.; Gun’ko, V.M.; Turov, V.V.; Krupska, T.V.; Pakhlov, E.M.; Zhang, D.; Dong, W.; Le, Z. Nanostructured Polymethylsiloxane/Fumed Silica Blends. Materials 2019, 12, 2409.

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