Recent Advances in Aerogel-Based Composites

A special issue of Gels (ISSN 2310-2861). This special issue belongs to the section "Gel Analysis and Characterization".

Deadline for manuscript submissions: closed (20 April 2024) | Viewed by 11573

Special Issue Editor

School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro–Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
Interests: novel two-dimensional materials; point-of-care detection; energy conversion; electrochemistry
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Special Issue Information

Dear Colleagues,

Aerogels, which feature ultra-low density, high porosity, and large specific surface area, are advanced structures currently receiving a great deal of interest. Aerogels were first created by S. S. Kistler in 1931 and further developed in the 1970s based on silica and similar materials. Since then, aerogels (carbon aerogels, metallic aerogels, cellulose aerogels, etc.) and their synthesis processes have been widely reported. At present, aerogels are attracting intensive research attention in the areas of thermal insulation, electrochemical energy storage and conversion, electromagnetic interference shielding, catalysis and sensing applications.

Although many efforts have been devoted to the achievement of aerogels-based materials with desired and tunable properties, there are still many opportunities and challenges to be addressed. Their morphology, pore structure, composition, defects and crystallinity have a great influence on their physicochemical properties and quality; hence, the procedures for aerogel production and precise structural control are of great importance. Especially, it is challenging to maintain the microstructure of gels during the drying process. Currently, with improved and efficient methods to obtain aerogels, satisfactory performance in their application has been achieved at lab-scale. However, aerogels can only become available on the market when their preparation is low-cost and large-scale. There are many technical barriers which need to be overcome in order to realize the transformation from lab to industrial scale.

In this Special Issue, we aim to share up-to-date strategies in aerogel fabrication, structure control and large-scale production. We welcome papers discussing not only single-compound aerogels but also the design and functionality of hybrid aerogels. We believe that the development of aerogels with appropriate or tunable properties will present promising opportunities in various fields.

Dr. Xiao Li
Guest Editor

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Keywords

  • functional aerogels
  • hybrid aerogels
  • 3D porous structure
  • physicochemical properties
  • large-scale production
  • applications

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Related Special Issue

Published Papers (5 papers)

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Research

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13 pages, 11949 KiB  
Article
Hydrophobic Silk Fibroin–Agarose Composite Aerogel Fibers with Elasticity for Thermal Insulation Applications
by Yuxiang Du, Pengjie Jiang, Xin Yang, Rui Fu, Lipeng Liu, Changqing Miao, Yaxiong Wang and Huazheng Sai
Gels 2024, 10(4), 266; https://doi.org/10.3390/gels10040266 - 15 Apr 2024
Cited by 2 | Viewed by 1410
Abstract
Aerogel fibers, characterized by their ultra-low density and ultra-low thermal conductivity, are an ideal candidate for personal thermal management as they hold the potential to effectively reduce the energy consumption of room heating and significantly contribute to energy conservation. However, most aerogel fibers [...] Read more.
Aerogel fibers, characterized by their ultra-low density and ultra-low thermal conductivity, are an ideal candidate for personal thermal management as they hold the potential to effectively reduce the energy consumption of room heating and significantly contribute to energy conservation. However, most aerogel fibers have weak mechanical properties or require complex manufacturing processes. In this study, simple continuous silk fibroin–agarose composite aerogel fibers (SCAFs) were prepared by mixing agarose with silk fibroin through wet spinning and rapid gelation, followed by solvent replacement and supercritical carbon dioxide treatment. Among them, the rapid gelation of the SCAFs was achieved using agarose physical methods with heat-reversible gel properties, simplifying the preparation process. Hydrophobic silk fibroin–agarose composite aerogel fibers (HSCAFs) were prepared using a simple chemical vapor deposition (CVD) method. After CVD, the HSCAFs’ gel skeletons were uniformly coated with a silica layer containing methyl groups, endowing them with outstanding radial elasticity. Moreover, the HSCAFs exhibited low density (≤0.153 g/cm3), a large specific surface area (≥254.0 m2/g), high porosity (91.1–94.7%), and excellent hydrophobicity (a water contact angle of 136.8°). More importantly, they showed excellent thermal insulation performance in low-temperature (−60 °C) or high-temperature (140 °C) environments. The designed HSCAFs may provide a new approach for the preparation of high-performance aerogel fibers for personal thermal management. Full article
(This article belongs to the Special Issue Recent Advances in Aerogel-Based Composites)
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13 pages, 1596 KiB  
Article
Effects of Freeze-Drying Processes on the Acoustic Absorption Performance of Sustainable Cellulose Nanocrystal Aerogels
by Ju-Qi Ruan, Kai-Yue Xie, Jun-Nan Wan, Qing-Yuan Chen, Xiaoqing Zuo, Xiaodong Li, Xiaodong Wu, Chunlong Fei and Shanshan Yao
Gels 2024, 10(2), 141; https://doi.org/10.3390/gels10020141 - 12 Feb 2024
Cited by 2 | Viewed by 2507
Abstract
Cellulose aerogels have great prospects for noise reduction applications due to their sustainable value and superior 3D interconnected porous structures. The drying principle is a crucial factor in the preparation process for developing high-performance aerogels, particularly with respect to achieving high acoustic absorption [...] Read more.
Cellulose aerogels have great prospects for noise reduction applications due to their sustainable value and superior 3D interconnected porous structures. The drying principle is a crucial factor in the preparation process for developing high-performance aerogels, particularly with respect to achieving high acoustic absorption properties. In this study, multifunctional cellulose nanocrystal (CNC) aerogels were conveniently prepared using two distinct freeze-drying principles: refrigerator conventional freezing (RCF) and liquid nitrogen unidirectional freezing (LnUF). The results indicate that the rapid RCF process resulted in a denser CNC aerogel structure with disordered larger pores, causing a stronger compressive performance (Young’s modulus of 40 kPa). On the contrary, the LnUF process constructed ordered structures of CNC aerogels with a lower bulk density (0.03 g/cm3) and smaller apertures, resulting in better thermal stability, higher diffuse reflection across visible light, and especially increased acoustic absorption performance at low–mid frequencies (600–3000 Hz). Moreover, the dissipation mechanism of sound energy in the fabricated CNC aerogels is predicted by a designed porous media model. This work not only paves the way for optimizing the performance of aerogels through structure control, but also provides a new perspective for developing sustainable and efficient acoustic absorptive materials for a wide range of applications. Full article
(This article belongs to the Special Issue Recent Advances in Aerogel-Based Composites)
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15 pages, 1868 KiB  
Article
Towards Understanding Aerogels’ Effect on Construction Materials: A Principal Component Analysis Approach
by Emil Obeid, Hamdi Chaouk, Rabih Mezher, Eddie Gazo Hanna, Omar Mouhtady, Jalal Halwani and Khaled Younes
Gels 2023, 9(12), 935; https://doi.org/10.3390/gels9120935 - 28 Nov 2023
Cited by 1 | Viewed by 1363
Abstract
This study investigates the applicability of Principal Component Analysis (PCA) for distinguishing construction materials. The approach enhances data presentation, revealing distinct clusters and variable impacts on materials. This perspective provides valuable insights into concrete materials, guiding materials science and engineering practices. Our findings [...] Read more.
This study investigates the applicability of Principal Component Analysis (PCA) for distinguishing construction materials. The approach enhances data presentation, revealing distinct clusters and variable impacts on materials. This perspective provides valuable insights into concrete materials, guiding materials science and engineering practices. Our findings show the capacity of PCA to show a clear distinction between concrete and non-concrete composites. Compressive strength significantly affects certain composites, being influenced by aerogel loading. The peculiar role of aerogel density among the other factors is attributed to their possession of the smallest thermal conductivity. To address moderate total variance of PCA, segregation into concrete (C) and non-concrete (NC) categories is explored, offering a more robust distinction and higher clustering. Concrete materials show higher variance, emphasizing the effectiveness of the segregation approach. PCA highlights aerogel density’s influence on thermal conductivity on concrete materials. For non-concrete materials, a moderately higher variance is noted, emphasizing the critical role of aerogel-related properties (size and density). These findings underscore the importance of aerogel characteristics in shaping material behaviour. Full article
(This article belongs to the Special Issue Recent Advances in Aerogel-Based Composites)
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16 pages, 2772 KiB  
Article
Amino-Functionalized Cellulose Nanofiber/Lignosulfonate New Aerogel Adsorbent for the Removal of Dyes and Heavy Metals from Wastewater
by Islam Elsayed, Gregory T. Schueneman, Emad M. El-Giar and El Barbary Hassan
Gels 2023, 9(2), 154; https://doi.org/10.3390/gels9020154 - 14 Feb 2023
Cited by 21 | Viewed by 3272
Abstract
Due to the increasingly widespread water pollutants and the high cost of treatment methods, there is a demand for new, inexpensive, renewable, and biodegradable adsorbent materials for the purification of wastewater contaminants. In this study, a new biocomposite aerogel (Amf-CNF/LS) was prepared using [...] Read more.
Due to the increasingly widespread water pollutants and the high cost of treatment methods, there is a demand for new, inexpensive, renewable, and biodegradable adsorbent materials for the purification of wastewater contaminants. In this study, a new biocomposite aerogel (Amf-CNF/LS) was prepared using a chemically cross-linking method between the amino-functionalized cellulose nanofibers (Amf-CNF) and lignosulfonates (LS). The physical and chemical properties of the prepared aerogel were investigated using several techniques including elemental analysis, scanning electron microscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and N2 adsorption-desorption analysis. The Amf-CNF/LS aerogel was then applied for the removal of methylene blue (MB), rhodamine B dye (RhB), and the heavy metal cadmium ion (Cd2+) from synthetic wastewater solutions. The adsorption parameters controlling the adsorption process including the pH, contact time, adsorbent dosage, and adsorbate concen-tration were optimized. High adsorption kinetics and isotherms were observed, with the adsorption isotherms of the Amf-CNF/LS aerogel fitting the Langmuir model with maximum adsorption capacities of 170.94, 147.28, and 129.87 mg/g for MB, RhB, and Cd2+, respectively. These results show that Amf-CNF/LS aerogel is a promising green and inexpensive adsorbent for MB, RhB, and Cd2+ removal from wastewater. Full article
(This article belongs to the Special Issue Recent Advances in Aerogel-Based Composites)
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Review

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21 pages, 3368 KiB  
Review
Graphene-Based Aerogels for Biomedical Application
by Yeongsang Kim, Rajkumar Patel, Chandrashekhar V. Kulkarni and Madhumita Patel
Gels 2023, 9(12), 967; https://doi.org/10.3390/gels9120967 - 9 Dec 2023
Cited by 4 | Viewed by 2485
Abstract
Aerogels are three-dimensional solid networks with incredibly low densities, high porosity, and large specific surface areas. These aerogels have both nanoscale and macroscopic interior structures. Combined with graphene, the aerogels show improved mechanical strength, electrical conductivity, surface area, and adsorption capacity, making them [...] Read more.
Aerogels are three-dimensional solid networks with incredibly low densities, high porosity, and large specific surface areas. These aerogels have both nanoscale and macroscopic interior structures. Combined with graphene, the aerogels show improved mechanical strength, electrical conductivity, surface area, and adsorption capacity, making them ideal for various biomedical applications. The graphene aerogel has a high drug-loading capacity due to its large surface area, and the porous structure enables controlled drug release over time. The presence of graphene makes it a suitable material for wound dressings, blood coagulation, and bilirubin adsorption. Additionally, graphene’s conductivity can help in the electrical stimulation of cells for improved tissue regeneration, and it is also appropriate for biosensors. In this review, we discuss the preparation and advantages of graphene-based aerogels in wound dressings, drug delivery systems, bone regeneration, and biosensors. Full article
(This article belongs to the Special Issue Recent Advances in Aerogel-Based Composites)
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