Effect of synthesis temperature on the ordered pore structure in mesoporous silica studied by positron annihilation spectroscopy

Li, C.Y.; Qi, N. D.; Liu, Z.W.; Zhou, Bo; Chen, Z.Q.; Wang, Z.

doi:10.1016/j.apsusc.2015.12.055

Cited by 17 publications

(7 citation statements)

References 40 publications

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“…However, there are boundaries to the temperature used in all SBA-15 and KIT-6 synthesis processes. The use of a high temperature is necessary for the formation of mesoporous materials, through the condensation of hydroxyls, to form siloxane bonds, but several studies have demonstrated the effects on the quality of the temperature-related MNS formation used during a static hydrothermal synthesis of SBA-15 [53][54][55] and KIT-6 [5]. Nevertheless, during the calcination process, these bonds are consolidated, giving rise to the desired material when the largest loss of surface silanol groups occurs; however, too great a loss leaves the material unusable for functionalization.…”

Section: Introductionmentioning

confidence: 99%

Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials

et al. 2020

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The calcination process is a crucial step during SBA-15 and KIT-6 synthesis. It is used to completely remove the organic template and condense silanol groups, and it allows the determination of the textural and physical properties of these materials, depending on the adopted conditions. Moreover, calcination influences the number of silanols available on the surface of the material. The concentration of silanols is important if these materials were synthesized for use in adsorption or functionalization. To understand and optimize the silanol groups of SBA-15 and KIT-6, in this study, the temperature and time calcination parameters were varied. The experiments were performed at 300, 400, and 500 °C for 300, 400, and 500 min. The results show that the ideal temperature to preserve the silanol groups is 300 °C, but to optimize the textural properties, it is better to calcine these molecular sieves at 400 °C. A calcination for 10 h did not give better results than a calcination for 5 h, demonstrating that the former duration is excessive for use.

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Section: Introductionmentioning

confidence: 99%

Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials

et al. 2020

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“…The employment of MS is strictly related to its physical-chemical properties, documented by numerous literature examples demonstrating the versatility of MCM-41 synthesis to produce particles with specific structures, morphologies, sizes, or surface properties. , A complete resume of the synthetic approaches is beyond the scope of this manuscript, and many of them are discussed elsewhere. ,, It is worth mentioning that, in the last 30 years, several studies have focused on the control of the particle characteristics, leading to specific syntheses finalized to a specific purpose . The modulation of reaction temperature, pH, or time and generally the type or the amount of surfactant or silica precursor were studied to observe the effects mainly on the pore size , and sometimes on the particle size and morphology . The Taguchi method (a statistical approach based on experimental data to control the particle size by changing synthetic conditions) has been adopted to evaluate the effectiveness of some parameters, like the pH value of silica/surfactant solution, reaction time, and silica precursor (tetraethyl-orthosilicate, TEOS) amount .…”

Section: Introductionmentioning

confidence: 99%

“…12,13,15 It is worth mentioning that, in the last 30 years, several studies have focused on the control of the particle characteristics, leading to specific syntheses finalized to a specific purpose. 16 The modulation of reaction temperature, 17 pH, 18 or time 19 and generally the type or the amount of surfactant 20 or silica precursor 21 were studied to observe the effects mainly on the pore size 22,21 and sometimes on the particle size 23 and morphology. 24 The Taguchi method (a statistical approach based on experimental data to control the particle size by changing synthetic conditions) has been adopted to evaluate the effectiveness of some parameters, like the pH value of silica/surfactant solution, reaction time, and silica precursor (tetraethyl-orthosilicate, TEOS) amount.…”

Section: ■ Introductionmentioning

confidence: 99%

Design Rules for Mesoporous Silica toward the Nanosize: A Systematic Study

Catalano

Pompa

2019

ACS Appl. Mater. Interfaces

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Mesoporous silica nanoparticles (MSNs) are one of the most frequently employed inorganic materials for catalysis and nanomedicine applications. Nonetheless, a complete control of MSN synthesis parameters aimed at standardizing particle properties is still far from complete, being one of the reasons underlying heterogeneity in their chemical−physical properties, as well as in their biological outcomes. Here, transmission electron microscopy, Xray diffraction, and volumetric analysis, together with dynamic light scattering and ζ-potential measurements, were combined to carefully characterize different MSNs through a systematic investigation of the role and effectiveness of different factors, such as reaction temperature, time, and pH, on the resulting particle size, texture, and dispersion properties. This methodological approach allowed the implementation of design rules for size-, shape-, and structurecontrolled MSNs in the range between 170 and 50 nm.

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“…As shown in Table 1 , the radius R f of the free-volume holes decreased from 3.92 Å to 3.82 Å as the weight ratio of crosslinker rose from 0.2 wt.% to 1.5 wt.%, and the R f remained basically unchanged when the weight ratio exceeded 1.5 wt.%. However, the variation o f o -Ps was small as the weight ratio of crosslinker changed [ 33 , 34 ].

…”

Section: Resultsmentioning

confidence: 99%

Influence of Crosslinking Extent on Free Volumes of Silicone Rubber and Water Diffusion after Corona Discharge

et al. 2022

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Silicone rubber is widely used as an insulating material. In this article, silicone rubber samples were prepared by varying the content of crosslinker (2,5-bis(tert-butyl-peroxy)-2,5-dimethylhexane, DBPMH), and the free volume holes in the samples were investigated by means of positron annihilation lifetime spectroscopy (PALS) measurement. The surface chemical structure, surface micromorphology and water diffusion of the samples after corona discharge treatment were studied by FTIR, SEM and EIS measurements, respectively. As the crosslinker weight ratio increased from 0.2 wt.% to 1.5 wt.%, the mean free volume hole size first decreased and then remained unchanged. However, the concentration of free volume holes did not vary as the crosslinker weight ratio increased. SEM morphologies show that surface cracks were produced on samples having high crosslinking levels after corona treatment. The water diffusion coefficient of samples after corona treatment increased from 3.13 × 10−10 cm2 s−1 to 17.68 × 10−10 cm2 s−1 in the initial immersion period, as the crosslinker weight ratio increased from 0.2 wt.% to 3.0 wt.%. The results indicated that deterioration of samples with high crosslinking levels were more serious and water repellency more easily lost. The corona resistance ability of low crosslinking level silicone rubber stems from internal low molecular weight molecules.

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Effect of synthesis temperature on the ordered pore structure in mesoporous silica studied by positron annihilation spectroscopy

Cited by 17 publications

References 40 publications

Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials

Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials

Design Rules for Mesoporous Silica toward the Nanosize: A Systematic Study

Influence of Crosslinking Extent on Free Volumes of Silicone Rubber and Water Diffusion after Corona Discharge

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