Polyurea Aerogels: Synthesis, Material Properties, and Applications

Leventis, Nicholas

doi:10.3390/polym14050969

Cited by 31 publications

(27 citation statements)

References 95 publications

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“…In general, in fibrous and porous materials, the acoustic attenuating mechanism can be divided into three categories: , (i) vibration and friction of air molecules with the cavity walls or fibers, (ii) periodic compression and release of air inside cavities, and (iii) resonance between sound wave and cavity walls and fibers. Among the commonly used prediction models of porous sound absorption materials, the Johnson–Champoux–Allard model is the most widely used prediction model of porous fiber materials (see Supporting Information Methods).…”

Section: Resultsmentioning

confidence: 99%

Highly Efficient Thermo-Acoustic Insulating Aerogels Enabled by Resonant Cavity Engineering

Zhou

Yang

et al. 2023

ACS Nano

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Lightweight, flexible, and noncombustible thermo-acoustic insulating (TAI) materials have great potential in vehicles, cold-chain transportation, and aerospace engineering, where weight and space savings are critical. However, the TAI capabilities of many commodities are hindered by the lack of diverse and reasonable resonant cavities with broadband and highly efficient acoustic responsiveness. This study demonstrates a layer-by-layer freeze-casting method for superelastic cellular aerogel construction from varied nanofibers and ice particulates with widely distributed resonant cavities from 0.5 to 300 μm. The method enabled the cumulative freezing of the nanofiber solution from one side to the other side, resulting in vertical pore channels with random holes across the entire freezing distance. The formed cellular networks of stable hinged ternary nanofiber membranes, functionalized as ultrathin nanofiber drums, exhibit strong resonances and efficiently dissipate sound waves in a broad frequency range. A high noise reduction coefficient of 0.65 at a frequency range of 63–6300 Hz and a low thermal conductivity of 0.026 W m–1 K–1 at room temperature was obtained. This work presents the bottom-up fabrication of high-performance TAI aerogels that are beneficial for practical energy-saving devices and buildings and broadband acoustic absorption applications.

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Section: Resultsmentioning

confidence: 99%

Highly Efficient Thermo-Acoustic Insulating Aerogels Enabled by Resonant Cavity Engineering

Zhou

Yang

et al. 2023

ACS Nano

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“…The finely structured porous skeletal framework together with the small size pores provides aerogels with unique properties, among which are higher surface areas, low thermal conductivities, low dielectric constants, and high acoustic attenuation [75]. Interestingly, the nanostructure of the aerogels can be designed and tuned by choosing specific monomers [93][94][95][96][97] or by modifying the synthetic procedure [98][99][100][101][102][103][104][105].…”

Section: Aerogelsmentioning

confidence: 99%

Uranium Removal from Aqueous Solutions by Aerogel-Based Adsorbents – A critical review

Georgiou¹,

Raptopoulos²,

Anastopoulos³

et al. 2022

Preprint

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Aerogel-based adsorbents present extraordinary sorption capacity for hexavalent uranium that can be as high as 8.8 mol kg–1 (2088 g kg–1). The adsorption data follow generally the Langmuir isotherm model and the kinetic data are better described by the pseudo-second-order kinetic model, which is associated with chemisorption. Evaluation of the thermodynamic data reveals that the adsorption is generally an endothermic, entropy-driven process (ΔHo, ΔSo > 0). Spectroscopic studies (e.g., FTIR, XPS) indicate that the adsorption is based on the formation of in-ner-sphere complexes between surface active moieties and the uranyl cation. Regeneration and uranium recovery by acidification and complexation using carbonate or chelating ligands (e.g., EDTA) have been found to be successful. The application of aerogel-based adsorbents to uranium removal from industrial processes and uranium-contaminated waste waters was also successful, assuming that these materials could be very attractive as adsorbents in water treatment and uranium recovery technologies. However, the selectivity of the studied materials towards hexavalent uranium is limited suggesting further development of aerogel materials which could be modified by surface derivatization with chelating agents (e.g., salophen, iminodiacetate) presenting high selectivity for uranyl moieties.

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“…The finely structured porous skeletal framework together with the small-sized pores provides aerogels with unique properties, among which are high surface areas, low thermal conductivities, low dielectric constants, and high acoustic attenuation [ 76 ]. Interestingly, the nanostructure of the aerogels can be designed and tuned by choosing specific monomers [ 94 , 95 , 96 , 97 , 98 ] or by modifying the synthetic procedure [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 ].…”

Section: Introductionmentioning

confidence: 99%

Uranium Removal from Aqueous Solutions by Aerogel-Based Adsorbents—A Critical Review

et al. 2023

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Aerogels are a class of lightweight, nanoporous, and nanostructured materials with diverse chemical compositions and a huge potential for applications in a broad spectrum of fields. This has led the IUPAC to include them in the top ten emerging technologies in chemistry for 2022. This review provides an overview of aerogel-based adsorbents that have been used for the removal and recovery of uranium from aqueous environments, as well as an insight into the physicochemical parameters affecting the adsorption efficiency and mechanism. Uranium removal is of particular interest regarding uranium analysis and recovery, to cover the present and future uranium needs for nuclear power energy production. Among the methods used, such as ion exchange, precipitation, and solvent extraction, adsorption-based technologies are very attractive due to their easy and low-cost implementation, as well as the wide spectrum of adsorbents available. Aerogel-based adsorbents present an extraordinary sorption capacity for hexavalent uranium that can be as high as 8.8 mol kg–1 (2088 g kg–1). The adsorption data generally follow the Langmuir isotherm model, and the kinetic data are in most cases better described by the pseudo-second-order kinetic model. An evaluation of the thermodynamic data reveals that the adsorption is generally an endothermic, entropy-driven process (ΔH0, ΔS0 > 0). Spectroscopic studies (e.g., FTIR and XPS) indicate that the adsorption is based on the formation of inner-sphere complexes between surface active moieties and the uranyl cation. Regeneration and uranium recovery by acidification and complexation using carbonate or chelating ligands (e.g., EDTA) have been found to be successful. The application of aerogel-based adsorbents to uranium removal from industrial processes and uranium-contaminated waste waters was also successful, assuming that these materials could be very attractive as adsorbents in water treatment and uranium recovery technologies. However, the selectivity of the studied materials towards hexavalent uranium is limited, suggesting further developments of aerogel materials that could be modified by surface derivatization with chelating agents (e.g., salophen and iminodiacetate) presenting high selectivity for uranyl moieties.

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Polyurea Aerogels: Synthesis, Material Properties, and Applications

Cited by 31 publications

References 95 publications

Highly Efficient Thermo-Acoustic Insulating Aerogels Enabled by Resonant Cavity Engineering

Highly Efficient Thermo-Acoustic Insulating Aerogels Enabled by Resonant Cavity Engineering

Uranium Removal from Aqueous Solutions by Aerogel-Based Adsorbents – A critical review

Uranium Removal from Aqueous Solutions by Aerogel-Based Adsorbents—A Critical Review

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