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Gun'ko, V.М.; Dyachenko, A. G.; Borysenko, M.V.; Skubiszewska–Zięba, J.; Лебода, Р.

doi:10.1023/a:1015270523926

Cited by 18 publications

(20 citation statements)

References 24 publications

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“…At T r > 700 K the probability of the TiCl 4 interaction with ≡Si−O−Si≡ to form ≡Si−Cl bonds increases, that leads to titania consolidation and an increase in the area of contacts between the grafted titania particles and the silica matrix, and a rutile portion in titania deposits increases [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The Si−O−Ti bridges are hydrolytically unstable; therefore, the excess of water in the reaction medium leads to the formation of segregated titania particles [25][26][27][28][29][30][31][32][33][34][35]. Different precursors were used to synthesize titania, e.g., TiX 4 at X = Cl, OCH(CH 3 ) 2 and other OR [41][42][43][44][45][46][47] which could be transformed through oxidation, hydrolysis/dehydration, and thermal decomposition to form titania.…”

Section: Introductionmentioning

confidence: 99%

Titania deposits on nanosilicas

Gun'ko¹,

Богатырев²,

Лебода³

et al. 2009

Annales UMCS, Chemistry

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Titania (content C TiO2 = 2.7-20.0 wt%) was synthesized on different fumed silica substrates (A-50, A-100, A-380) using Ti[OCH(CH 3 ) 2 ] 4 as a precursor interacting with silica/adsorbed water in 2-propanol or CCl 4 medium, dried and then heated at 1073 K for 1 h. Initial and pretreated nanosilicas and titania/silicas were studied using XRD, adsorption, FTIR, TEM, AFM, and TPD-MS methods. The morphology of grafted titania (anatase/rutile/amorphous phase composition, particle size distribution, aggregation, textural porosity) depends on the types of a nanosilica matrix and a solvent, suspension treatments and reaction conditions.

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Section: Introductionmentioning

confidence: 99%

Titania deposits on nanosilicas

Gun'ko¹,

Богатырев²,

Лебода³

et al. 2009

Annales UMCS, Chemistry

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“…4), with less change in nanoparticle size (Figs. 2 and 3), e.g., observed during hydrothermal treatment of silicas [37].…”

Section: Figmentioning

confidence: 99%

“…The freezing of aqueous suspensions of nanosilica in high-pressure reactors results in dried powdered materials that are very different from silicas treated in vapor phase water at high pressures and temperatures [30][31][32][33][34][35][36][37], at high temperatures and normal pressure in air [38], or at room temperature and normal pressure followed by air drying [39][40][41]. The air-dried high-pressure cryosilicas are in the powder state with agglomerates of 1-20 m in size (Fig.…”

Section: Effects Of Freezing Conditions On the Particle Morphology Anmentioning

confidence: 99%

“…This is due to re-arrangement of nanoparticles in aggregates and agglomerates of aggregates during suspension and subsequent drying. Primary particles become mobile in sonicated aqueous suspensions including a large proportion of individual nanoparticles [32][33][34][35][36][37][38][39][40][41].…”

Section: Effects Of Freezing Conditions On the Particle Morphology Anmentioning

confidence: 99%

“…During drying of the suspensions, nanoparticles tend to form more compacted aggregates and agglomerates than those formed in the flame (flow velocity > 20 m/s) during pyrogenic synthesis [32][33][34][35][36][37][38][39][40][41]. There is empty volume (V em = 1/ b -1/ 0 ) of the powder, which is directly links to the bulk density  b and true density ( 0 = 2.2 g/cm 3 ) of silicas.…”

Section: Effects Of Freezing Conditions On the Particle Morphology Anmentioning

confidence: 99%

See 2 more Smart Citations

High-pressure cryogelation of nanosilica and surface properties of cryosilicas

Gun’ko

Туров

Zarko

et al. 2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Gun'ko, V M.; Turov, V V.; Zarko, V I.; Prykhod'ko, G P.; Remez, O S.; Leboda, R; Skubiszewska-Zieba, J; Pahklov, E M.; and Blitz, Jonathan, "High-pressure cryogelation of nanosilica and surface properties of cryosilicas" (2013 AbstractSilica cryogels (cryosilicas) in a powder state were synthesized with different concentrations of fumed silica A-300 (C A-300 = 5-20 wt.%), sonicated in aqueous suspension, then frozen at 14 o C at different pressures in a high-pressure stainless steel reactor (a freezing bomb), and dried in air at room temperature. To analyze the effects of low temperature and high pressure, samples were also prepared at 14 o C or room temperature and standard pressure. The structural and adsorption properties of the powder materials were studied using nitrogen adsorption, highresolution transmission electron microscopy, infrared spectroscopy, thermogravimetry, lowtemperature 1 H NMR spectroscopy and thermally stimulated depolarization current. The structural, textural, adsorption and relaxation characteristics of high-pressure cryogel hydrogels and related dried powders are strongly dependent on the silica content in aqueous suspensions frozen at 1, 450 or 1000 atmospheres and then dried. The largest changes are found with C A-300 = 20 wt.% which are analyzed with respect to the interfacial behavior of nonpolar, weakly polar and polar adsorbates using low temperature 1 H NMR spectroscopy.

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Dielectric and thermal studies of segmental dynamics in silica/PDMS and silica/titania/PDMS nanocomposites

Sulym

Klonos

Borysenko

et al. 2014

J of Applied Polymer Sci

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Effects of silica and silica/titania nanoparticles on glass transition and segmental dynamics of poly(dimethylsiloxane) (PDMS) were studied for composites of a core–shell type using differential scanning calorimetry, thermally stimulated depolarization current, and dielectric relaxation spectroscopy techniques. Strong interactions between the filler and the polymer suppress crystallinity (Tc, Xc) and affect significantly the evolution of the glass transition in the nanocomposites. The segmental relaxation associated with the glass transition consists of three contributions, arising, in the order of decreasing mobility, from the bulk (unaffected) amorphous polymer fraction (α relaxation), from polymer chains restricted between condensed crystal regions (αc relaxation), and from the semi‐bound polymers in an interfacial layer with strongly reduced mobility due to interactions with surface hydroxyls of silica and silica/titania nanoparticles (α′ relaxation). The evolution of surface affected CH3 groups, as well as the degree of interaction of PDMS molecules with surface hydroxyl groups as a function of treatment temperature, was assessed by Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis. The effectiveness of silica/PDMS and silica/titania/PDMS nanocomposites as hydrophobic coatings was investigated by static contact angle measurements. It was shown that the presence of titania nanoparticles and adsorbed PDMS promotes the hydrophobic properties of the PDMS coating after treatment in the 80–650°C range. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41154.

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Cited by 18 publications

References 24 publications

Titania deposits on nanosilicas

Titania deposits on nanosilicas

High-pressure cryogelation of nanosilica and surface properties of cryosilicas

Dielectric and thermal studies of segmental dynamics in silica/PDMS and silica/titania/PDMS nanocomposites

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