书目名称 | Springer Handbook of Aerogels | 编辑 | Michel A. Aegerter,Nicholas Leventis,Stephen A. St | 视频video | http://file.papertrans.cn/875/874957/874957.mp4 | 概述 | Covers best practices for materials characterization and equipment design.Features in-depth coverage of all types of organic, inorganic, and composite aerogels, from silica based aerogels to polymer a | 丛书名称 | Springer Handbooks | 图书封面 |  | 描述 | .This indispensable handbook provides comprehensive coverage of the current state-of-the-art in inorganic, organic, and composite aerogels – from synthesis and characterization to cutting-edge applications and their potential market impact. Built upon Springer’s successful Aerogels Handbook published in 2011, this handbook features extensive revisions and timely updates, reflecting the changes in this fast-growing field. .Aerogels are the lightest solids known to man. Up to 1000 times lighter than glass and with a density only four times that of air, they possess extraordinarily high thermal, electrical, and acoustic insulation properties, and boast numerous entries in Guinness World Records. Originally based on silica, R&D efforts have extended this class of materials to incorporate non-silicate inorganic oxides, natural and synthetic organic polymers, carbon, metal, and ceramic materials. Composite systems involving polymer-crosslinked aerogels and interpenetrating hybrid networks have been developed and exhibit remarkable mechanical strength and flexibility. Even more exotic aerogels based on clays, chalcogenides, phosphides, quantum dots, and biopolymers such as chitosan are op | 出版日期 | Book 2023 | 关键词 | inorganic aerogel; organic aerogel; composite aerogel; exotic aerogel; history of aerogels; properties of | 版次 | 1 | doi | https://doi.org/10.1007/978-3-030-27322-4 | isbn_ebook | 978-3-030-27322-4Series ISSN 2522-8692 Series E-ISSN 2522-8706 | issn_series | 2522-8692 | copyright | Springer Nature Switzerland AG 2023 |
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Front Matter |
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Abstract
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,The Story of Aerogel, |
Stephen A. Steiner III,Alain C. Pierre |
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Abstract
In this handbook, we explore the diverse class of porous materials called aerogels – what they are, how they are made, how they are characterized, materials properties they can exhibit, their applications, and their increasing role in commerce. In this chapter, we provide the reader with a general introduction to the topic of aerogels and an overview of their history.
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Overview of the Sol–Gel Process |
Plinio Innocenzi |
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Abstract
The first studies on sol–gel processing have been very much focused on the possibility of obtaining bulk gels and through these glasses from a low temperature route. With the time this first idea has been almost abandoned and sol-gel inorganic chemistry has become something different. Nowadays it is an almost ubiquitous process in nano-chemistry to prepare a variety of different materials in the form of films, membranes, nanoparticles, aerogels, mesoporous and microporous materials, self-assembled materials, etc. This change of perspective has brought to an unexpected success of inorganic and hybrid sol-gel chemistry which is now a very popular tool for nanoscience. At the same time, part of the interest in the basic chemistry of the process has been lost which has also made many people unaware of the fundamental scientific background. The complexity of sol-gel chemistry represents a natural limitation to our capability of giving very detailed and fine descriptions of complex processes..In this chapter, some basic elements of sol-gel chemistry would be introduced with the purpose of giving a general overview and describing the main properties of sol-to-gel transition which is the p
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Gel-Phase Processing and Solvent Exchange |
Justin S. Griffin,Ryan T. Nelson,Pavel Gurikov,Irina Smirnova,Stephen A. Steiner III |
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Abstract
Several important unit operations involved in aerogel production pertain to the formation and processing of gels. Formation of a gel typically occurs in a mold, and accordingly, important considerations should be given to gel molding. Furthermore, after a gel has been formed, additional processing steps are typically required before its pore fluid can be removed to produce an aerogel. Such steps include aging of the gel to strengthen its solid-phase backbone, diffusion-mediated replacement of its pore fluid with a target solvent to compatibilize the gel for drying, and optional liquid-phase chemical treatment(s), for example, to impart hydrophobicity, introduce a desired functionality, or increase strength. This chapter discusses important unit operations including molding and demolding, aging, and solvent exchange, as well as examples of liquid-phase chemical treatments used to prepare various functional aerogels.
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Supercritical Drying of Aerogels |
Raman Subrahmanyam,Ilka Selmer,Alberto Bueno,Dirk Weinrich,Wibke Lölsberg,Marc Fricke,Sohajl Movahhe |
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Abstract
In this chapter, we discuss the process of supercritical drying as it relates to the production of aerogels. What was once a heuristic technique typically performed using overly conservative process rules can now be quantitatively designed and efficiently implemented. Herein, thermodynamic and kinetic considerations of supercritical drying are reviewed along with practical aspects and process-engineering considerations at both the lab and industrial scale. Finally, considerations for process scale-up and further development of aerogel production processes are presented.
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Freeze Drying |
Justin S. Griffin,Massimo F. Bertino,Tyler M. Selden,Sylwia M. Członka,Stephen A. Steiner III |
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Abstract
Freeze drying is a technique that can be used to remove the pore fluid from a gel to produce an aerogel. In this process, the pore fluid of a gel is frozen and then subsequently sublimed to leave behind the gel’s solid skeleton without substantial collapse of its porosity. In some instances, freeze drying can be used instead of supercritical drying to yield aerogels of comparably high quality. In this chapter, the science of freeze drying is discussed along with important considerations regarding its application to aerogels. Examples from the literature of how freeze drying has been used to make aerogels are also provided.
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Postprocessing |
Stephen A. Steiner III,Justin S. Griffin,Ryan T. Nelson,Frances I. Hurwitz,Marcus A. Worsley |
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Abstract
In this chapter, processing steps that are performed on an aerogel in its dry state, or . steps, are described. While many aerogel properties and structural features can be tailored during gel-phase processing, other aspects cannot be modified or cannot easily be modified until after liquid has been removed from the gel. Furthermore, some aerogels are not produced via wet gel precursors, and thus can only be modified in their dry state. Through postprocessing, the surface chemistry of an aerogel can be tailored, amorphous oxide aerogels can be crystallized into specific phases, polymer aerogels can be converted into carbon aerogels, and shaped aerogels with features too complex to mold can be produced. In this chapter, common examples of postprocessing steps used in the production of aerogels, including vapor-phase functionalization, annealing, pyrolysis, and shape control, are discussed.
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Structural Characterization of Aerogels |
Gudrun Reichenauer |
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Abstract
Determining reliable structural parameters for an aerogel by applying suitable characterization techniques is a key factor in terms of understanding the different synthesis steps and their impact on the resulting aerogel. Combining structural parameters with the physical properties of the material allows optimization for specific applications. It is only the profound knowledge of the structure–properties relationships that provides access to the full potential of this type of material. This chapter presents different characterization methods commonly used and discusses their potential and limitations. Furthermore, more recent developments and new approaches are introduced.
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Mechanical Characterization of Aerogels |
Huiyang Luo,Sadeq Malakooti,Habel Gitogo Churu,Nicholas Leventis,Hongbing Lu |
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Abstract
As multifunctional porous nanostructured materials (e.g., thermally/acoustically insulating), aerogels are derived from their vast porosity and their high specific surface area and may also hold exceptional specific mechanical properties under certain conditions as well. In this chapter, the mechanical characteristics of aerogels are discussed in detail. First, the mechanical characterization of traditional aerogels is summarized, and then, the mechanical behavior of polymer crosslinked silica and vanadia (X-aerogels), as well as organic aerogels, is presented. Finally, the acoustic attenuation property is briefly discussed for polyurea aerogel. In polymer crosslinked aerogels, a few-nanometer-thick conformal polymer is coating on secondary particles, while the pores is not clogging, which thus preserves the multifunctionality of the native framework and improves the mechanical strength. The mechanical properties were characterized under both quasi-static loading conditions (dynamic mechanical analysis, compression, and flexural bending testing) and high-strain-rate loading conditions using a split Hopkinson pressure bar. We evaluated the effects of strain rate, mass density, loadi
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Thermal Properties of Aerogels |
Hans-Peter Ebert |
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This chapter provides an insight into the different aspects of heat transfer in aerogels and their thermal properties. In this context, the principle heat transfer mechanisms are discussed and illustrated by exemplary experimental results. Additionally, various experimental methods are presented allowing the analyses of the different aspects of heat transfer. Typical thermal conductivity values and radiative properties as well as their dependency on external conditions such as temperature or atmosphere are discussed for different classes of aerogels. This chapter concludes with a brief discussion about the specific heat of aerogels.
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Permeability of Silica Aerogels |
Thierry Woignier,Liz Anez,Sylvie Calas-Etienne,Juan Primera,Pascal Etienne,Jean Phalippou |
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Abstract
Silica aerogels have many potential applications, including as host matrices for chemical species or nuclear waste storage. For these applications, the permeability is a key parameter and data show that the silica aerogels have poor permeability (~10–60 nm.). In this chapter we review the method to measure the liquid and gas permeability in gels, aerogels, and composite aerogels. Ideally, permeability does not depend on the type of pore fluid, therefore permeability measured using gas should be the same as that measured using water. We measured gas and water permeability in sets of nanocomposite silica aerogels. Experimental results show that gas permeability in aerogels was larger than water permeability by almost two orders of magnitude. The observed difference in gas and water permeability was analyzed from the point of view of the slip regime (Klinkenberg correction) and transition regime (Knudsen correction); the slip flow of gas at pore walls enhances the gas flow when pore sizes are small. This work addresses the problem of estimating permeability with high porosity materials such as aerogels. The effects of structural parameters of porous media (pore volume, tortuosity, fra
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Simulation and Modeling of Aerogels Using Atomistic and Mesoscale Methods |
Lev D. Gelb |
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Abstract
Molecular modeling and simulation are now widely used in many areas of materials science. In this chapter, we consider the application of these techniques to developing a better understanding of the microscopic structure of aerogels and how this gives rise to their unique properties. The great majority of aerogel simulations to date have focused on silica aerogels. Early studies were concerned primarily with realistic reproduction of aerogel structure, in particular the fractal dimension, but more recent work has turned toward accurate modeling of aerogel mechanics and other properties. Simulation studies of aerogels have made use of atomistic modeling approaches, “coarse-grained” models, and multiscale models that integrate atomistic and coarse-grained information; these will all be reviewed, and the various positive and negative aspects of each approach will be considered. Finally, challenges facing this field will be discussed, including extension of simulation studies to aerogels based on materials other than silica.
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Modeling the Structural, Fractal and Mechanical Properties of Aerogels |
Ameya Rege |
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Modeling and simulation have played an indispensable role in the understanding of the structure-property relationships of a wide class of materials. Material modeling has been pivotal in enhancing our understanding of several aspects of porous materials, including those that of aerogels. This chapter summarizes the role of modeling and simulation in investigating specifically the mechanical structure-property relationships of aerogels. The role of all-atom simulations in describing the nanomechanics of aerogels is first examined. This is followed by a review of aggregation models and their impact on the characterization of the structural and fractal properties of aerogels. Constitutive models and their role in predicting the overall macroscopic behavior of aerogels are then discussed in detail. More recent microstructure-based approaches, such as Voronoi tessellations and the bonded particle method, applied for describing the morphology of aerogels and their subsequent properties are considered at the end.
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Silica Aerogels |
Alain C. Pierre,Arnaud Rigacci |
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Abstract
The present review is focused on one of the most studied aerogel materials, silica aerogels. It aims at presenting a brief overview of the elaboration steps (sol–gel synthesis, ageing, and drying), the textural and chemical characteristics (aggregation features, porosity and surface chemistry), the main physical properties (from thermal, mechanical, acoustical, and optical to biological, medical, etc.) and a rather broad panel of related potential applications of these fascinating nanostructured materials. It cannot be considered as an exhaustive synopsis but must be used as a simple tool to initiate further bibliographic studies on silica aerogels, which are amazing very light solid materials, as shown in Fig. 13.1.
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Hydrophobic Silica Aerogels |
Ann M. Anderson,Mary K. Carroll |
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Abstract
There are many applications for which a material must be water-resistant. Hydrophobicity, in combination with the other unusual properties of silica aerogels (high surface area, low density, low thermal conductivity, and good optical translucency), renders these materials attractive for use in applications ranging from transparent insulation systems to drug delivery platforms. The hydrophobicity of silica aerogels can be tailored through incorporation of silica precursors with nonpolar substituents into a sol–gel matrix or through surface modification of the matrix following gelation. In this chapter we describe the different aerogel synthesis methods, present a discussion of techniques for measuring hydrophobicity and review the extensive literature on hydrophobic silica aerogels, including information on their physical properties and applications.
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Superhydrophobic and Flexible Aerogels and Xerogels Derived from Organosilane Precursors |
Kazuyoshi Kanamori,Ana Stojanovic,Gerard M. Pajonk,Digambar Y. Nadargi,A. Venkateswara Rao,Kazuki Na |
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Abstract
The field of organosilane-derived aerogels is a rather young area of aerogel research. Inherently, organosilane precursors offer the advantage that they already contain at least one direct Si-C bond in the silane precursor, thus imparting specific chemical functionality. In particular, if used exclusively to prepare organo-modified polysiloxane aerogels, hydrophobicity originating from the organic substituent group(s) can bypass the need for a second post-modification (hydrophobization) step. Pioneered by early works, recent years have brought tremendous improvements in terms of methodology; combination with organic, hybrid (polymerization-based) chemistries, as well as ambient-drying protocols. Modern organosilane-based preparation techniques are cost-competitive with conventional silica aerogel synthetic routes but offer a tremendous added value potential through the use of suitable “secondary functionalization” protocols, particularly obvious in many examples in the form of improved mechanical properties (bendability, machinability, higher toughness, and e-modulus) but also improved resistance against organic solvents. This chapter gives an overview over this trendsetting and co
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Sodium Silicate-Based Aerogels by Ambient Pressure Drying |
A. Venkateswara Rao,Shanyu Zhao,Gerard M. Pajonk,Uzma K. H. Bangi,A. Parvathy Rao,Matthias M. Koebel |
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Silica aerogels are the most commercially relevant aerogel materials. By volume, supercritically dried blanket composites are still leading global sales by a substantial amount; however, particle-based aerogels such as granulate and powder are cost-competitive alternatives. This chapter summarizes the last three decades of research and industrial process development in the field of “low-cost,” sodium silicate-based aerogel preparation by means of ambient pressure drying, illustrating key developments and milestones in both academic research and process engineering fields. Key process steps such as gelation, aging, hydrophobization, and APD drying are analyzed in detail in the context of feasibility, simplicity, product quality, and scalability. The chapter finishes with a brief discussion of key process parameters and their effect on the physical properties of the obtained aerogel materials as well as a current snapshot of the most promising applications for particle-based aerogels.
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