Spectral changes in Si–O–Si stretching band of porous glass network upon ingress of water

Kaya, Hüseyin; Ngo, Dien; Gin, Stéṕhane; Kim, Seong H.

doi:10.1016/j.jnoncrysol.2019.119722

Cited by 35 publications

(29 citation statements)

References 35 publications

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“…Description of silica particles in terms of structures and porosity has been widely based on the analysis of IR spectra [ 50 , 51 , 52 , 53 , 54 , 55 ]. IR studies are particularly valuable because of the high polarity of silicon-oxygen bonds.…”

Section: Resultsmentioning

confidence: 99%

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

et al. 2021

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Mesoporous silica nanostructures (MSNs) attract high interest due to their unique and tunable physical chemical features, including high specific surface area and large pore volume, that hold a great potential in a variety of fields, i.e., adsorption, catalysis, and biomedicine. An essential feature for biomedical application of MSNs is limiting MSN size in the sub-micrometer regime to control uptake and cell viability. However, careful size tuning in such a regime remains still challenging. We aim to tackling this issue by developing two synthetic procedures for MSN size modulation, performed in homogenous aqueous/ethanol solution or two-phase aqueous/ethyl acetate system. Both approaches make use of tetraethyl orthosilicate as precursor, in the presence of cetyltrimethylammonium bromide, as structure-directing agent, and NaOH, as base-catalyst. NaOH catalyzed syntheses usually require high temperature (>80 °C) and large reaction medium volume to trigger MSN formation and limit aggregation. Here, a successful modulation of MSNs size from 40 up to 150 nm is demonstrated to be achieved by purposely balancing synthesis conditions, being able, in addition, to keep reaction temperature not higher than 50 °C (30 °C and 50 °C, respectively) and reaction mixture volume low. Through a comprehensive and in-depth systematic morphological and structural investigation, the mechanism and kinetics that sustain the control of MSNs size in such low dimensional regime are defined, highlighting that modulation of size and pores of the structures are mainly mediated by base concentration, reaction time and temperature and ageing, for the homogenous phase approach, and by temperature for the two-phase synthesis. Finally, an in vitro study is performed on bEnd.3 cells to investigate on the cytotoxicity of the MNSs.

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Section: Resultsmentioning

confidence: 99%

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

et al. 2021

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“…These samples are of great interest because their r r differ by approximately a factor of 6, i.e., r r (pH7) = ∼6•r r (pH9) 29,30 . The gels formed in these experiments have been deeply investigated at different stages of the reaction 27,[29][30][31][32][33][34] , and more samples are still under corrosion and thus available for further investigations. Previous characterizations concluded that the gel composition, pore volume, pore size, and structure are similar at pH 7 and pH 9, only their thickness differs significantly (by a factor ∼6) 27,[29][30][31][32][33][34] .…”

Section: Introductionmentioning

confidence: 99%

Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses

et al. 2020

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Borosilicate glasses are widely used to confine high-level radioactive wastes. The lifetime of these materials could reach hundreds of thousands of years if leaching of the glass into groundwater enables the formation of a passivating gel layer. Even in this regime, the glass will never stop corroding as thermodynamic equilibrium between glass and solution cannot be achieved. Therefore, accurate predictions of glass durability including passivation, require a deep understanding of the mechanisms controlling the so-called residual rate. However, despite tremendous efforts, these mechanisms remain poorly understood. Here, focusing on the behavior of the soluble elements of the International Simple Glass (B, Na, and Ca), we show that the residual rate is controlled by the behavior of B, a glass former supposed to dissolve instantaneously when in contact with water and thus widely considered as an ideal tracer. We then demonstrate that B release is controlled by multiple processes highly dependent on the pH. At the beginning of the passivating layer formation, the hydrolysis of B-O-Si linkages is rate-limiting and has an activation energy of ∼60 kJ mol−1, a value slightly lower than that for breaking Si-O-Si linkages. Once the fraction of closed pores resulting from gel restructuring is high enough, then diffusion of both reactants (water molecules) and some products (mainly Baq, Caaq) through the growing gel layer becomes rate-limiting. Consequently, B and Ca accumulate in an inner layer referred to as the active zone, with potential feedback on the B-O-Si hydrolysis. A new paradigm, including B as a key element of the system, is proposed to develop a comprehensive model for the corrosion of borosilicate glass.

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“…Figure 5e revealed the small minimum at 1198 cm -1 , ascribed to symmetric Si-O stretching vibration [110]. Minimum positioned at 1090 cm -1 is related to the asymmetric Si-O stretching vibration [110], while the minimum at 1073 cm -1 could be attributed to the stretching vibration of the Si-O-Si bridging oxygen [96]. Minimum at 796 cm -1 is assigned to the Si-O-Si bending vibrations [110].…”

Section: Ftir Measurementsmentioning

confidence: 95%

“…In the cases of some silica phases, this type of error is a consequence of the lack of knowledge about the true crystal symmetry of the represented phase [88], which results in different selection rules for classification of the vibrations of the same silica phase. Consequently, non-uniform ascription of the same vibrations to different silica bonds modes can be found in literature [89][90][91][92][93][94][95][96][97].…”

Section: Ftir Measurementsmentioning

confidence: 99%

The Influence of Thermal Treatment on the Formation Mechanism of the Cu, Fe-Containing Nanocomposite Material Synthesized by the Sol–Gel Method

et al. 2021

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The nanocomposite samples, containing copper and iron species in the silica matrix, were prepared by annealing at temperatures up to 1100°C. The samples were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and cyclic voltammetry. The results of the performed study depict to the presence of a temperature gradient, which acts on the sample during the annealing treatment in the furnace. For the first time, the influence of the temperature gradient on the formation mechanism of the samples was discussed.

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Spectral changes in Si–O–Si stretching band of porous glass network upon ingress of water

Cited by 35 publications

References 35 publications

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses

The Influence of Thermal Treatment on the Formation Mechanism of the Cu, Fe-Containing Nanocomposite Material Synthesized by the Sol–Gel Method

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