Internal and external surface characterisation of templating processes for ordered mesoporous silicas and carbons

Hill, Matthew; Izgorodina, Ekaterina I.; Mudie, Stephen; Kennedy, Danielle F.; Hill, Anita J.

doi:10.1039/b817457a

Cited by 14 publications

(16 citation statements)

References 58 publications

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“…After burning out the Amberlite support at the same conditions from the acid set SiHP-A, its total pore volume and BET surface area substantially increased without measurable changes in the average mesopore diameter as data for Si-A demonstrate in Table 1. This is only possible when the microporosity increases in this material which could not be determined from these N 2 adsorption data, but the roughly doubled 29 Si NMR spectra illustrate that different molecular constitutions cause the differences in physical appearance of silica gels. Spectra and pictures are from ref.…”

Section: Resultsmentioning

confidence: 91%

“…Solid state 29 Si Magic-Angle Spinning (MAS) NMR spectra were obtained at 59.6 MHz resonance frequency on a Bruker Avance-300 spectrometer at room temperature using 4 mm zirconia rotors with 8 kHz spinning speed. Typically 8000 scans resulted in satisfactory signal-to-noise ratio.…”

Section: Si Nmrmentioning

confidence: 99%

“…20,21 In the course of the past few years, an entirely different, efficient approach, positronium annihilation lifetime spectroscopy (PALS) has been developed and used successfully for characterizing a wide range of pores simultaneously without using any adsorbate molecules or cooling the probe . [22][23][24][25][26][27][28][29] For positronium, when used as a probe molecule, the free volumes in solids look and physically indeed remain, empty. In principle the PALS probe can also be used at most practical temperatures, at which porous materials are employed.…”

Section: Introductionmentioning

confidence: 99%

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Positron annihilation and N2 adsorption for nanopore determination in silica-polymer composites

et al. 2012

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Silica has two different, fragmented and smooth, visual appearances when deposited onto porous Amberlite polymer substrate from TEOS at acidic and basic pH, respectively. The low temperature N 2 adsorption isotherms on both materials seem to be a combination of Type 1 and Type 4 isotherms with H2 hysteresis, indicating the presence of both micro (D , 2 nm diameter) and meso (2 nm , D , 50 nm) pores. Their mesopore distributions, computed by both BJH and DFT methods, show maxima near Dy5 nm with a narrower pore size distribution range than the organic support alone. For comparison, pores were also tested by positron annihilation lifetime spectroscopy (PALS) which can scan the full micro to mezo size range in one measurement without cooling and using any adsorbate molecules. These PALS results indicated the presence of Dy0.5, 0.8 and 1.5 nm diameter micropores and an average Dy5 nm diameter mesopores in both the base and the acid set materials. When the organic substrate is burned out from the two differently made composites, the new adsorption isotherms, BET surface areas, and differently measured pore sizes became distinctly different both from each other and from those of the parent materials.

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Section: Resultsmentioning

confidence: 91%

Section: Si Nmrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Positron annihilation and N2 adsorption for nanopore determination in silica-polymer composites

et al. 2012

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“…The decrease in measured surface area could be due to the accessibility of the pores by the N 2 gas ~ 9 ~ probe. 30 When examining the PSD, Figure 4, it can be seen that the distribution of pore sizes in these mesoporous materials is very broad, spaning ca. 25 nm.…”

Section: Resultsmentioning

confidence: 99%

Disordered Mesoporous Gadolinosilicate Nanoparticles Prepared Using Gadolinium Based Ionic Liquid Emulsions: Potential as Magnetic Resonance Imaging Contrast Agents

et al. 2011

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Gadolinium doped mesoporous silica (gadolinosilicate) nanoparticles were synthesized using a novel approach aimed at incorporating Gd ions into a porous silica network. The ionic liquid, gadolinium (Z)-octadec-9-enoate (Gd Oleate) was utilized in a dual role, as a soft template to generate porous silica and also to act as a gadolinium source for incorporation into the silicate. The generated silicate materials were characterized for size, structure and composition, confirming that gadolinium was successfully doped into the silicate network in a mesoporous nanoparticulate form. Proton relaxivity results indicated that the gadolinium doped silicates had slightly lower longitudinal relaxivity and much higher transverse relaxivity than the commercial contrast agent Magnevist®, suggesting that the mesoporous nanoparticulate materials have potential as contrast agents for magnetic resonance imaging.

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“…Moreover, this technique provides reliable information concerning changes in any free volumes with diameters below 2 nm up to several tens of nanometers. Its usefulness for investigation of various free spaces, which include mesopores (He et al 2013;Hill et al 2009), micropores (Kullmann et al 2010), and even intermolecular free volumes (Zgardzińska and Goworek 2015) has already been recognized.…”

Section: Introductionmentioning

confidence: 99%

Positron porosimetry study of mesoporous polymer–silica composites

et al. 2016

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The polymer-SiO 2 composites prepared using polymers with different chemical composition and porosity (i.e. XAD4, XAD16, and XAD7) as well as series of composites synthesized with different contents of silica species and at different pH were investigated. The study was conducted to compare the results of nitrogen adsorption and positron porosimetry for these three sets of samples. The possible causes of the inconsistency between the results of both methods are discussed. The impact of the chemical character of the polymer support surface on the final properties of the polymer-silica composite was found to be greater than its porosity (i.e. the shape of pores and their connectivity). Changing the SiO 2 content influences mostly the pore volume of composites. To significantly modify their pore size distribution, more than 30 wt% of silica species are required. The composite synthesized at pH 5 has the widest pore size distribution among all samples supported by XAD7. The discrepancies concerning the porosity derived with both methods are the smallest for composites where XAD7 was used as the support. This allows determination of the relation V = (3.38 V PALS -0.03) cm 3 /g, which may be useful for estimation of pore volumes corresponding to those found by nitrogen adsorption.

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Internal and external surface characterisation of templating processes for ordered mesoporous silicas and carbons

Cited by 14 publications

References 58 publications

Positron annihilation and N2 adsorption for nanopore determination in silica-polymer composites

Positron annihilation and N2 adsorption for nanopore determination in silica-polymer composites

Disordered Mesoporous Gadolinosilicate Nanoparticles Prepared Using Gadolinium Based Ionic Liquid Emulsions: Potential as Magnetic Resonance Imaging Contrast Agents

Positron porosimetry study of mesoporous polymer–silica composites

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