Melting and freezing of water in ordered mesoporous silica materials

Schreiber, Andreas; Ketelsen, Ingke; Findenegg, Gerhard H.

doi:10.1039/b010086m

Cited by 446 publications

(590 citation statements)

References 27 publications

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“…Here, as done in the aforementioned experiments (neutron and NMR) (10, 11), we used as confining system a micelle-templated nanoporous silica matrix MCM-41-S (having 1D cylindrical tubes arranged in a hexagonal structure with a pore diameter of 1.4 nm) (10, 21). As proven by several experimental methods, this MCM system can be regarded as one of the most suitable adsorbent models available (22,23). In particular, it has been shown that in such a system, water dynamics is weakly affected by confinement effects.…”

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confidence: 99%

Evidence of the existence of the low-density liquid phase in supercooled, confined water

Mallamace

Broccio

Corsaro

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

279

297

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By confining water in a nanoporous structure so narrow that the liquid could not freeze, it is possible to study properties of this previously undescribed system well below its homogeneous nucleation temperature T H ‫؍‬ 231 K. Using this trick, we were able to study, by means of a Fourier transform infrared spectroscopy, vibrational spectra (HOH bending and OH-stretching modes) of deeply supercooled water in the temperature range 183 < T < 273 K. We observed, upon decreasing temperature, the building up of a new population of hydrogen-bonded oscillators centered around 3,120 cm ؊1 , the contribution of which progressively dominates the spectra as one enters into the deeply supercooled regime. We determined that the fractional weight of this spectral component reaches 50% just at the temperature, T L Ϸ 225 K, where the confined water shows a fragile-to-strong dynamic cross-over phenomenon dynamic cross-over in water ͉ dynamic transitions in water ͉ Fourier transform infrared spectroscopy ͉ low-density liquid water ͉ Widom line in water W ater plays a fundamental and ubiquitous role on Earth and in all aspects of life phenomena. Understanding its properties is of paramount importance to mankind, and thus water is the most studied molecular system in science and technology. However, despite intense scrutiny over the years, scientists are still far from reaching a coherent understanding of all its unusual properties (1-3). Instead of behaving like other simple molecular liquids, many thermodynamic response functions of water, such as the isothermal compressibility, isobaric heat capacity, and thermal expansion coefficient, display counterintuitive trends as temperature is lowered. In particular, extrapolated from their values at moderately supercooled states, these functions all appear to diverge at a singular temperature around T S ϭ 228 K. Over the years, many plausible explanations for these strange behaviors have been proposed, starting from the two-state and the clathrate models (1-3). Three hypotheses are of active interest: (i) the stability limit (4), (ii) the percolation (5), and (iii) liquid-liquid (LL) critical point (6). The third approach has received support from various theoretical studies (7-9). However, in all three approaches, the main role is played by the local hydrogen-bond (HB) interaction pattern surrounding a typical water molecule in liquid state that governs the overall structure and dynamics (1) of water. Some of our recent experimental results (10, 11) on water confined in nanoporous structures as a function of temperature and pressure showed that the theoretical approach based on existence of the LL critical point is able to describe coherently many strange properties of water. By using the neutronscattering technique, we obtained evidence of the LL critical point (the second critical point predicted by the theory to be at T C ϳ 220 K and P C ϳ 1 kbar) located at T C ϭ 200 K and P C ϭ 1.5 kbar (10). This result was also subsequently confirmed qualitatively by an extensive molecular dynam...

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mentioning

confidence: 99%

Evidence of the existence of the low-density liquid phase in supercooled, confined water

Mallamace

Broccio

Corsaro

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

279

297

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“…In case of water TPM, this factor was investigated by a few authors but only with partially filled pores. Schreiber et al [27] or Findenegg et al [40] observed that whereas melting scans exhibited only a single peak, two or three peaks appeared in the freezing scans, depending of the degree of pore filling. They attributed this behaviour to the existence of two or more distinct arrangements of solid and liquid in the pores.…”

Section: Resultsmentioning

confidence: 99%

“…In order to use the solid-to-liquid phase transition water as a thermoporosimetry probe, it is necessary to establish the mathematical relationships between the diameter of the pores (D) and the corresponding phase transition temperature depression DT. The overall trend for most thermoporosimetry experiments cited in the references is that of a linear dependence between DT and the inverse of pore radius 1/R p [24][25][26][27]. This assumption allows fitting experimental data to the modified Gibbs-Thomson equation which take into account the presence and thickness of the non-freezing liquid layer t (Eq.…”

Section: Resultsmentioning

confidence: 99%

“…However, they also confirm that for silicas with pore diameter bigger than 10 nm, the differences between water thermoporosimetry and nitrogen sorption outcomes become higher. Schmidt et al [25] Ishikiriyama and Todoki [26] Landry [24] Schreiber et al [27] NLDFT H2O-TPM:…”

Section: Resultsmentioning

confidence: 99%

“…The aim of this paper was to refine the water TPM method to make it more useful for wider spectrum of potential users by examining the influence of various parameters on the water TPM results, summarizing and simplifying the experimental protocol and establishing reliable calibration equations. Brun et al [15] Schmidt et al [25] Ishikiriyama and Todoki [26] Landry [24] Schreiber et al [27] Series of ordered mesoporous silicas SBA-15, differing by the hexagonal unit cell parameter a, was chosen as model materials because of the ease in tailoring the uniform mesopores of various diameters and relatively thick silica walls which provide high stability and ensure long storage time [28]. Additionally, the method was checked by study porous properties of functionalized silica material obtained by anchoring of the N- [3-(trimethoksysilil)prophyl]etylenodiamine (AEAPTS) functional group on the internal and/ or external surface of SBA-15.…”

Section: Introductionmentioning

confidence: 99%

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Water thermoporosimetry as a tool of characterization of the textural parameters of mesoporous materials

Majda

Zimowska

Tarach

et al. 2016

J Therm Anal Calorim

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Water thermoporosimetry (TPM) is a powerful method for studying the properties of porous materials, devoted especially for investigation of the samples that can be destroyed in drying process. However, this method is not very popular and relatively rarely used because of problems with proper measurement procedure and choosing correct equation for the result interpretation. This report focused on refinement of general experimental protocols for water TPM. For the first time, the role of various parameters on the TPM outcomes was deeply investigated and simple and fast experimental mode was proposed. Additionally, based on the series of mesoporous silica SBA-15, the calibration procedure was employed and the reliable calibration equations were established.

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