From hard to rubber-like: mechanical properties of resorcinol–formaldehyde aerogels

Schwan, Marina; Naikade, Manoj; Raabe, Dierk; Ratke, Lorenz

doi:10.1007/s10853-015-9094-x

Cited by 22 publications

(16 citation statements)

References 26 publications

(39 reference statements)

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“…According to our experiments, the stirring time doubles for samples of 1000 mL, at the same time 60 min are sufficient for 100 mL samples. Aerogels prepared from insufficiently stirred sols, which did not gel completely, have another microstructure and are semi-flexible as reported previously [16]. They exhibit big particles of 2-5 m and big pores in the range of 10-20 m. The formation of this kind of structure is caused by promoted addition reactions during short stirring and a long condensation step.…”

Section: Influence Of Ph and Stirring Time On The Gelation Ratiosupporting

confidence: 63%

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New soft and spongy resorcinol–formaldehyde aerogels

Schwan

Tannert

Ratke

2016

The Journal of Supercritical Fluids

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Section: Influence Of Ph and Stirring Time On The Gelation Ratiosupporting

confidence: 63%

“…They observed that macroscopic flexibility is indirectly affected by the molecular properties of the monomers. We recently reported the synthesis of low-flexible RF aerogels dried under ambient conditions [16]. Such aerogels are elastically deformable up to 16% and have a very low Young's modulus of about 65-150 kPa.…”

Section: Introductionmentioning

confidence: 99%

New soft and spongy resorcinol–formaldehyde aerogels

Schwan

Tannert

Ratke

2016

The Journal of Supercritical Fluids

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“…On the contrary, MOAs with long aspect ratio fibers render a larger amount of empty areas, thus preventing breakage and conferring plasticity upon material. Specific compressive strength measured for the toughest MOAs (NiDTA‐100: 12725 J kg −1 ; NiDTA‐50: 1662 J kg −1 ; and PdDTA: 258 J kg −1 ) is far higher than that found for the unique MOF‐aerogel mechanically characterized, and somewhat higher than many carbon, organic, ceramic, and metal aerogels, and comparable to some conventional polymeric foams like polystyrene, polyurethane, etc. (Figure b).…”

Section: Resultsmentioning

confidence: 81%

Chemically Resistant, Shapeable, and Conducting Metal‐Organic Gels and Aerogels Built from Dithiooxamidato Ligand

Vallejo-Sánchez

Amo‐Ochoa

Beobide

et al. 2017

Adv Funct Materials

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Metal‐organic gels (MOGs) appear as a blooming alternative to well‐known metal‐organic frameworks (MOFs). Porosity of MOGs has a microstructural origin and not strictly crystalline like in MOFs; therefore, gelation may provide porosity to any metal‐organic system, including those with interesting properties but without a porous crystalline structure. The easy and straightforward shaping of MOGs contrasts with the need of binders for MOFs. In this contribution, a series of MOGs based on the assembly of 1D‐coordination polymer nanofibers of formula [M(DTA)]n (MII: Ni, Cu, Pd; DTA: dithiooxamidato) are reported, in which properties such as porosity, chemical inertness, mechanical robustness, and stimuli‐responsive electrical conductivity are brought together. The strength of the MS bond confers an unusual chemical resistance, withstanding exposure to acids, alkalis, and mild oxidizing/reducing chemicals. Supercritical drying of MOGs provides ultralight metal‐organic aerogels (MOAs) with densities as low as 0.03 g cm−3 and plastic/brittle behavior depending on the nanofiber aspect ratio. Conductivity measurements reveal a semiconducting behavior (10−12 to 10−7 S cm−1 at 298 K) that can be improved by doping (10−5 S cm−1). Moreover, it must be stressed that conductivity of MOAs reversibly increases (up to 10−5 S cm−1) under the presence of acetic acid.

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“…A reduction in the amount of catalyst results in an increase in particle size, reaching a size on the micrometer scale [62]. This was also observed in the synthesis of these aerogels since the R/C ratio was 1500 and the size of the polymer particles was given on the micrometer scale due to prolonged condensation during synthesis [63]. The interparticle pores observed by this technique (SEM) have a scale of micrometre's, therefore, they are not efficient in the adsorption of CO 2 , this process occurs in the intra-particular pores studied in Section 3.1.2.…”

Section: Infrared Spectroscopymentioning

confidence: 67%

Kinetic and Equilibrium Study of the Adsorption of CO2 in Ultramicropores of Resorcinol-Formaldehyde Aerogels Obtained in Acidic and Basic Medium

Romero

Moreno–Piraján

Gutiérrez

2018

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In this work, aerogels were prepared using resorcinol-formaldehyde as a precursor in two synthetic routes, one basic and one acidic, to perform the adsorption of CO 2 at 0 • C and atmospheric pressure. Aerogels were Characterization by N 2 and CO 2 Physisorption, Raman Spectroscopy, Scanning Electron Microscopy, and Infrared Spectroscopy. In general, was found that aerogels have a polymeric, disordered, three-dimensional structure and have a microporous surface. Langmuir, Freundlich, Sips and Toth equilibrium models present a good data fit of CO 2 adsorption at relative pressure ranging between 1 × 10 −4 and 3 × 10 −2 . The diffusion intra-particle kinetic model explains the setps of this process; the Elovich model also showed a good fit, therefore, there are an energetic heterogeneity of the CO 2 superficial adsorption sites. The aerogel carbonized in basic medium at 1050 • C (ACB 1050) material was the best adsorbent of this pollutant, reaching an adsorption capacity of 6.43 mmol g −1 .Achieving economic and favorable separation of CO 2 from gas mixtures represents one of the main technological and environmental problems facing our society today [10]. The most studied post-combustion technology is chemical adsorption. Monoethanol amine (MEA) has been the chemical most used for this purpose. Alternative solvents, such as piperazine and ammonia, have also been proposed to achieve this objective [6]. The advantage of this method is the low partial pressure that is used because the CO 2 molecules are easily absorbed over liquids in flue gas streams [11]. The disadvantage is that the use of amine alkoxysilanes is very expensive [12], and the method requires high regeneration energy due to the large emission of combustion gases and the costs of repairing the process equipment [4]. Other common methods to achieve CO 2 sequestration include separation in membranes, cryogenic and biological methods, and physical adsorption [13].Capture and storage technology has been considered the best option to reduce carbon dioxide emissions from large sources, and particularly adsorption is considered a promising process to separate gas mixtures [14]. This process is inexpensive, requires less regeneration energy, is easy to handle, has fast kinetics, and has a high capacity of CO 2 adsorption and selectivity [4]. The adsorbents provide a high surface area, which is a fundamental parameter in this process. Among the different adsorbents, 13X zeolite has been investigated to adsorb CO 2 by oscillating the pressure [6]. It is generally recognized that CO 2 is physically adsorbed to activated carbon, mainly by condensation or liquefaction in pores with widths that are less than 1 nm [15]. The adsorption of this greenhouse gas in nanopore materials has also been investigated in zeolites exchanged with alkali metals, amino-modified and modified alkaline, mesoporous silicas, microporous polymers, carbons, and metalorganic structures [10]. It has also been established that the chemical properties of activated carbon play a relevant role in...

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From hard to rubber-like: mechanical properties of resorcinol–formaldehyde aerogels

Cited by 22 publications

References 26 publications

New soft and spongy resorcinol–formaldehyde aerogels

New soft and spongy resorcinol–formaldehyde aerogels

Chemically Resistant, Shapeable, and Conducting Metal‐Organic Gels and Aerogels Built from Dithiooxamidato Ligand

Kinetic and Equilibrium Study of the Adsorption of CO2 in Ultramicropores of Resorcinol-Formaldehyde Aerogels Obtained in Acidic and Basic Medium

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