Interfacial behavior of polar and nonpolar frozen/unfrozen liquids interacting with hydrophilic and hydrophobic nanosilicas alone and in blends

Vladimir V Turov; Vladimir M Gun'ko; Tetyana V Krupska; Mykola V Borysenko; Mykola T Kartel

doi:10.1016/j.jcis.2020.12.065

Interfacial behavior of polar and nonpolar frozen/unfrozen liquids interacting with hydrophilic and hydrophobic nanosilicas alone and in blends

J Colloid Interface Sci. 2021 Apr 15:588:70-83. doi: 10.1016/j.jcis.2020.12.065. Epub 2020 Dec 31.

Authors

Vladimir V Turov¹, Vladimir M Gun'ko², Tetyana V Krupska¹, Mykola V Borysenko¹, Mykola T Kartel¹

Affiliations

¹ Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv, Ukraine.
² Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv, Ukraine. Electronic address: vlad_gunko@ukr.net.

PMID: 33388588
DOI: 10.1016/j.jcis.2020.12.065

Abstract

Hypothesis: Various nanosilica characteristics depend on hydrophobization strongly affecting interfacial phenomena. Is it possible to prepare hydrophilic samples with hydrophobic silica (AM1) alone and in blends with hydrophilic one (A-300)? It can be done with addition of a small amount of water to the powders which then are mechanically treated.

Experiments: Nanosilicas were characterized using adsorption, desorption, microscopic, spectroscopic, and quantum chemistry methods. ¹H NMR spectroscopy and cryoporometry were applied to AM1 and AM1/A-300 blends wetted and mechanically treated. Wetted blends were studied with additions of n-decane and chloroform-d.

Findings: The powders wetted at h = 0.3-3.0 g of water per gram of dry solids have increased bulk density. Samples are in gel-like state at h = 4-5 g/g. Water interaction energy with nanoparticles nonmonotonically depends on h (maximal at h = 3 g/g). Upon mechanical treatment of wetted blends (h < 1.5 g/g), separated AM1 structures are absent. At greater h values, blend reorganization occurs to form AM1 aggregates covered by A-300 shells. Organics can displace water from mesovoids toward narrower pores inaccessible for larger molecules or into larger voids to reduce the contact area between immiscible liquids. Freezing point depression caused by confined space and dissolution effects is affected by the blend organization.

Keywords: Bound frozen/unfrozen n-decane; Bound frozen/unfrozen water; Chloroform dispersion medium effects; Hydrophilic/hydrophobic nanosilicas blends; Interfacial phenomena; NMR cryoporometry.