Nanoparticle–Loaded Aerogels and Layered Aerogels Cast from Sol–Gel Mixtures

Kim, Jiwon; Nakanishi, H.; Pollanen, J.; Smoukov, Stoyan K.; Halperin, W. P.; Grzybowski, Bartosz A.

doi:10.1002/smll.201100605

Cited by 12 publications

(10 citation statements)

References 50 publications

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“…By contrast, examples of synthetic materials exhibiting graded 3D structures are less common, mainly due to a lack of established synthetic procedures. Progress in method development has been made using, for example, layer-by-layer casting [15], 3D printing [16], gradient density gelation [17] or structuration via external forces [18]. Especially, the field of materials exhibiting nanoparticle gradients is highly interesting, reasoned by the improved catalytic activity of composite materials [19,20].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Magnetism in Gradient Porous Carbon Composite Aerogels

Bahner

Hug

Polarz

2021

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Porosity is of high importance for functional materials, as it allows for high surface areas and the accessibility of materials. While the fundamental interplay between different pore sizes and functionalities is quite well understood, few studies on gradually changing properties in a material exist. To date, only a few examples of such materials have been synthesized successfully. Herein, we present a facile method for synthesizing macroscopic carbon aerogels with locally changing pore sizes and functionalities. We used ultracentrifugation to fractionate differently functionalized and sized polystyrene nanoparticles. The assembly into gradient templates was conducted in a resorcinol–formaldehyde (RF) sol, which acted as a liquid phase and carbon precursor. We show that the modification of nanoparticles and a sol–gel precursor is a powerful tool for introducing dopants (sulfur and phosphorous) and metal nanoparticles (e.g., Ni) into gradient porous carbons formed during the carbonization of the RF sol. Understanding the underlying interactions between particles and precursors will lead to a plethora of possibilities in the material design of complex functionally graded materials. We showed this by exchanging parts of the template with magnetite–polystyrene composites as templating nanoparticles. This led to the incorporation of magnetite nanoparticles in the formed gradient porous carbon aerogels. Finally, gradually increasing concentrations of magnetite were obtained, ultimately leading to macroscopic carbon aerogels with locally changing magnetic properties, while the graded porosity was maintained.

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Section: Introductionmentioning

confidence: 99%

Anisotropic Magnetism in Gradient Porous Carbon Composite Aerogels

Bahner

Hug

Polarz

2021

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“…Combining these remarkable properties, aerogels have been considered for various applications, such as sensors [4], thermal insulators [5], catalyst supports [6][7][8][9], acoustic barriers [10], supercapacitors [11,12], water purification [13][14][15] and some aerospace applications [16,17]. Since silica aerogels were first created in 1931, silica-based aerogels have been the most popular aerogels.…”

Section: Introductionmentioning

confidence: 99%

Mechanically robust aerogels derived from an amine-bridged silsesquioxane precursor

Wang

Dai

Zhao

et al. 2015

J Sol-Gel Sci Technol

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A novel bridged silsesquioxane (BSQ) monomer was synthesized from 3-(2,3-epoxypropoxy)propyltrimethoxysilane and (3-aminopropyl)trimethoxysilane based on the reaction between epoxy and amine groups. The monomer was used to fabricate aerogels with excellent mechanical properties via sol-gel processes followed by supercritical CO 2 drying. The influence of the sol-gel conditions on the chemical structure, morphology and mechanical property of the aerogels was investigated by NMR, TGA, SEM, nitrogen sorption analysis and DMA. BSQ aerogels prepared from the optimal sol-gel procedure showed excellent properties with high mechanical performance (compression modulus of 20.4 MPa) and low density (0.22 g cm -3 ), which are of great advantage for practical applications. Further, SiO 2 /BSQ composite aerogels with significantly improved mechanical performance than SiO 2 aerogels can be obtained by co-condensing of BSQ monomer and tetraethoxysilane. The abundant hydroxyl groups in the BSQ precursor are believed to contribute to the robustness of BSQ and SiO 2 /BSQ composite aerogels due to the strengthened skeleton via the intermolecular H-bonds. Graphical AbstractKeywords Aerogel Á Bridged silsesquioxane Á Hybrid Á Robustness Á Sol-gel process

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“…16,17 Reaching beyond basic systems, hybrids made up of a host aerogel and nanoscale guest hold promise of combining the unique physical, chemical, and optical properties of both components to yield composite characteristics that could expand the scope of the applications of aerogel systems. 18,19 Silicon nanocrystals (SiNCs) are nontoxic quantum dots whose optical response may be tuned through variations of NC size and surface chemistry. 20−23 Because of their exquisitely tunable electronic, optical, and chemical properties, SiNCs have demonstrated prototype applications as active materials in sensors, 24,25 batteries, 26,27 bioimaging, 28,29 drug delivery, 22,30 optoelectronic structures, 31,32 and photovoltaics.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Silica aerogels have attracted substantial interest because of the relative ease with which they may be fabricated - they are readily prepared by exploiting the well-established principles of silicon sol–gel chemistry (i.e., the hydrolysis and condensation of silicon alkoxide precursors) and various drying procedures (e.g., supercritical drying, freeze-drying). Aerogels prepared in this way are transparent and possess specific surface areas approaching 500–1200 m 2 /g, porosities of 80–99.8%, and low densities (0.003–0.35 g/cm 3 ). , Reaching beyond basic systems, hybrids made up of a host aerogel and nanoscale guest hold promise of combining the unique physical, chemical, and optical properties of both components to yield composite characteristics that could expand the scope of the applications of aerogel systems. , …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Properties of Luminescent Silicon Nanocrystal/Silica Aerogel Hybrid Materials

et al. 2016

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Exploiting the chemical compatibility of transparent high surface area silica aerogels and environmentally benign luminescent silicon nanocrystals (SiNCs) opens the door to a new class of silicon-based hybrid materials. Hydrophilic SiNCs of various sizes and surface groups that photoluminesce throughout the visible and NIR spectral regions were synthesized and incorporated into tetramethyl orthosilicate containing solution to produce luminescent aerogels of varied transparency. Photoluminescence (PL) spectroscopy performed on solutions and aerogel monoliths containing SiNCs reveal that the optical properties of SiNCs are dependent on their size and surface chemistry. Furthermore, the incorporation of SiNCs into aerogels does not influence their PL response. The nitrogen adsorption-desorption measurements indicate that the physical properties of aerogels may be tailored by changing the SiNC size and surface chemistry.Adding to the appeal of the present work, PL quenching of SiNC-loaded aerogel upon exposure to nitrobenzene confirms that SiNCs remain chemically accessible.

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Nanoparticle–Loaded Aerogels and Layered Aerogels Cast from Sol–Gel Mixtures

Cited by 12 publications

References 50 publications

Anisotropic Magnetism in Gradient Porous Carbon Composite Aerogels

Anisotropic Magnetism in Gradient Porous Carbon Composite Aerogels

Mechanically robust aerogels derived from an amine-bridged silsesquioxane precursor

Synthesis and Properties of Luminescent Silicon Nanocrystal/Silica Aerogel Hybrid Materials

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