Effect of SiCl 4 on the preparation of functionalized mixed-structure silica from monodisperse sol–gel silica nanoparticles

Ruiz, Yolice Patricia Moreno; Cardoso, Mateus Borba; Ferrão, Marco Flôres; Moncada, Edwin; Santos, João Henrique Zimnoch dos

doi:10.1016/j.cej.2016.02.027

Cited by 25 publications

(19 citation statements)

References 51 publications

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“…indeed, no correlation between the type of porosity and our spheres size was found. By contrast, 19 as a distinguishing aspect, samples with different aging were chosen. In fact, our samples have different ages, being SFB-260 the eldest one (about ten years) and SFB-300 the newest one (one year).…”

Section: Porosity Quantificationmentioning

confidence: 99%

“…Nevertheless, the aforementioned considerations are often ignored and N 2 adsorption has habitually been used, even recently, for pore and surface characterization of Stöber and Stöbermodified particles without questioning its validity. 6,19,30,42,43 The knowledge of internal pore volume is indispensable to rationalize the properties of Stöber spheres and better know their functionalities. The pore characteristics define basic 4 magnitudes, such as the refractive index or the mass density, which are crucial to understand many systems integrating Stöber silica.…”

Section: Introductionmentioning

confidence: 99%

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Direct Measurement of Microporosity and Molecular Accessibility in Stöber Spheres by Adsorption Isotherms

et al. 2018

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The microporous nature of monodisperse Stöber silica spheres is demonstrated in the literature, although usually via indirect evidence. Contradictorily, there also exist numerous reports of nonporosity based on conventional N 2 adsorption isotherms, leading to a confusing scenario and questioning the evaluation methodology. Thus, there is the strong need of straight measure of microporosity in Stöber spheres, at best by available adsorption techniques, which must be further directly confronted with the standard nitrogen method. Here, for the first time, microporosity detection by N 2 and CO 2 adsorption are compared in Stöber spheres. We demonstrate that CO 2 isotherms at 273 K allows direct detection and quantification of the microporosity (about 0.1 cm 3 /g in our samples), while N 2 at 77 K cannot probe adequately the internal volume. We also show that a large amount of water fills the micropores under usual ambient conditions, also revealing the presence of small mesoporosity. Thus, the porous nature of Stöber spheres is investigated by a simple combination of adsorption isotherms, and the different accessibility of N 2 , CO 2 and H 2 O molecules are discussed. We emphasize the inadequacy of standard N 2 isotherms for micropore detection in Stöber silica, as the access of nitrogen molecules at cryogenic temperatures is kinetically restricted and may lead to erroneous 2 conclusions. Instead, we propose CO 2 isotherms as a simple and direct means for evaluation of microporosity.

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Section: Porosity Quantificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct Measurement of Microporosity and Molecular Accessibility in Stöber Spheres by Adsorption Isotherms

et al. 2018

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“…Size and structure are the key parameters determining the performance of the fabricated SNs/polyester composites, which should be finely controlled in the synthesis [95]. The approaches for the synthesis of SNs include chemical vapor deposition [23,96,97], flame synthesis [25,26], sol-gel method [98], and reverse microemulsion technology [99], etc. SNs synthesized by chemical vapor deposition have high purity and few surface hydroxyl groups, so they have excellent reinforcement performance and are mostly used for reinforcement of silicone rubber [100].…”

Section: Synthesis Of Snsmentioning

confidence: 99%

Emerging Applications of Silica Nanoparticles as Multifunctional Modifiers for High Performance Polyester Composites

et al. 2021

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Nano-modification of polyester has become a research hotspot due to the growing demand for high-performance polyester. As a functional carrier, silica nanoparticles show large potential in improving crystalline properties, enhancing strength of polyester, and fabricating fluorescent polyester. Herein, we briefly traced the latest literature on synthesis of silica modifiers and the resultant polyester nanocomposites and presented a review. Firstly, we investigated synthesis approaches of silica nanoparticles for modifying polyester including sol-gel and reverse microemulsion technology, and their surface modification methods such as grafting silane coupling agent or polymer. Then, we summarized processing technics of silica-polyester nanocomposites, like physical blending, sol-gel processes, and in situ polymerization. Finally, we explored the application of silica nanoparticles in improving crystalline, mechanical, and fluorescent properties of composite materials. We hope the work provides a guideline for the readers working in the fields of silica nanoparticles as well as modifying polyester.

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“…For both types of NPs, the employed synthetic approach plays a crucial role in controlling the subsequent features and hence the applications. Several scenarios have been reported in literature for the preparation of NPs, including the sol–gel (Stöber) method [ 11 , 15 , 16 , 17 , 18 , 19 , 20 ], co-precipitation [ 21 , 22 ], sonolysis [ 23 ], thermal decomposition of organometallics [ 24 ], and microemulsion [ 25 , 26 ]. Stöber method remains the dominant choice for coating process with the following advantages: (1) good dispersibility where no surfactants exist; (2) no agglomeration compared to microemulsion-based approach; and (3) the silica coat has terminal silanol group that can bind with variety of ligands.…”

Section: Introductionmentioning

confidence: 99%

“…In the current approach, one-step procedure employing Stöber synthesis will be employed to prepare the silica coat, while the modified traditional Mössbauer method will be used for preparing the magnetic core [ 27 ]. Surveying the literature shows that the influence of the synthetic conditions on the resulting nanocomposites is controversial [ 11 , 19 , 20 ]. It can, therefore, be concluded for a one-step approach, that any uncontrolled variation would have unfavorable impacts on the process itself as well as the properties of the resulting nanocomposites.…”

Section: Introductionmentioning

confidence: 99%

Smart Synthesis of Trimethyl Ethoxysilane (TMS) Functionalized Core–Shell Magnetic Nanosorbents Fe3O4@SiO2: Process Optimization and Application for Extraction of Pesticides

et al. 2020

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In the current study, a smart approach for synthesizing trimethyl ethoxysilane–decorated magnetic-core silica-nanoparticles (TMS-mcSNPs) and its effectiveness as nanosorbents have been exploited. While the magnetite core was synthesized using the modified Mössbauer method, Stöber method was employed to coat the magnetic particles. The objective of this work is to maximize the magnetic properties and to minimize both particle size (PS) and particle size distribution (PSD). Using a full factorial design (2k-FFD), the influences of four factors on the coating process was assessed by optimizing the three responses (magnetic properties, PS, and PSD). These four factors were: (1) concentration of tetraethyl-orthosilicate (TEOS); (2) concentration of ammonia; (3) dose of magnetite (Fe3O4); and (4) addition mode. Magnetic properties were calculated as the attraction weight. Scanning electron microscopy (SEM) was used to determine PS, and standard deviation (±SD) was calculated to determine the PSD. Composite desirability function (D) was used to consolidate the multiple responses into a single performance characteristic. Pareto chart of standardized effects together with analysis of variance (ANOVA) at 95.0 confidence interval (CI) were used to determine statistically significant variable(s). Trimethyl ethoxysilane–functionalized mcSNPs were further applied as nanosorbents for magnetic solid phase extraction (TMS-MSPE) of organophosphorus and carbamate pesticides.

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Effect of SiCl 4 on the preparation of functionalized mixed-structure silica from monodisperse sol–gel silica nanoparticles

Cited by 25 publications

References 51 publications

Direct Measurement of Microporosity and Molecular Accessibility in Stöber Spheres by Adsorption Isotherms

Direct Measurement of Microporosity and Molecular Accessibility in Stöber Spheres by Adsorption Isotherms

Emerging Applications of Silica Nanoparticles as Multifunctional Modifiers for High Performance Polyester Composites

Smart Synthesis of Trimethyl Ethoxysilane (TMS) Functionalized Core–Shell Magnetic Nanosorbents Fe3O4@SiO2: Process Optimization and Application for Extraction of Pesticides

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