Glossary, Acronyms and Abbreviations The following words listed in bold are written in italic in the contributions A A H 2 O/Na 2 SiO 3 molar ratio A23187 Calcium ionophore Absorption In chemistry, the process by which one substance, such as a solid or liquid, takes up another substance, such as a liquid or gas, through minute pores or spaces between its molecules. In physics, the process in which the incident radiated energy is retained without reflection or transmission on passing through a medium ACC Aerogel Cherenkov Counter Acidity Acid strength AC-ML Aerogel composite acoustic matching layer Acoustic impedance Ratio of particle velocity and the sound pressure Acoustic matching layer Antireflective layer of acoustic wave Acoustic velocity Velocity v of an acoustic wave as it travels across a solid, a liquid, a gas or a mixed material medium ADP Adenosine di-phosphate, a product which can be used to induce platelet aggregation Adsorption Surface phenomenon by which molecules of a gas or a liquid are fixed on the surface of a solid, with various types of bonding Adsorption isotherms Adsorption is usually described through isotherms, i.e., the amount of adsorbate on the adsorbent as a function of its pressure (if gas) or concentration (if liquid) at constant temperature Aerobic oxidation Oxidation by air under ambient conditions Aerocellulose Aerogels made from cellulose Aeroclay Aeroclays are clay-based aerogels generally elaborated by freeze-drying of clay-based hydrogels (for example, gels prepared with sodium-exchanged montmorillonite clay). It is accepted that the freeze-drying step results in a rearrangement of clay sheets to create the lightweight, oriented and porous structure of the final clay-based aerogel Aerocore An organic monolithic panel manufactured by American Aerogel Corporation Aerogels Defined by IUPAC as “Gels comprised of a microporous solid in which the dispersed phase is a gas” [see Pure Appl. Chem. 79(10):1801–1809, 2007]. However, the definition retained in this handbook is the one by Kistler, as “gels in which the liquid has been replaced by air, with very moderate shrinkage of the solid network” Aerogel functionalization Implementation of functional groups into aerogels AeroSand Sand bonded by aerogels M.A. Aegerter et al. (eds.), Aerogels Handbook, Advances in Sol-Gel Derived Materials and Technologies, DOI 10.1007/978-1-4419-7589-8, # Springer Science+Business Media, LLC 2011 893
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Glossary, Acronyms and Abbreviations
The following words listed in bold are written in italic in the contributions
A
A H2O/Na2SiO3 molar ratio
A23187 Calcium ionophore
Absorption In chemistry, the process by which one substance, such as a solid or liquid,
takes up another substance, such as a liquid or gas, through minute pores or spaces between
its molecules. In physics, the process in which the incident radiated energy is retained
without reflection or transmission on passing through a medium
ACC Aerogel Cherenkov Counter
Acidity Acid strength
AC-ML Aerogel composite acoustic matching layer
Acoustic impedance Ratio of particle velocity and the sound pressure
Acoustic matching layer Antireflective layer of acoustic wave
Acoustic velocity Velocity v of an acoustic wave as it travels across a solid, a liquid, a gasor a mixed material medium
ADP Adenosine di-phosphate, a product which can be used to induce platelet aggregation
Adsorption Surface phenomenon by which molecules of a gas or a liquid are fixed on the
surface of a solid, with various types of bonding
Adsorption isotherms Adsorption is usually described through isotherms, i.e., the amount
of adsorbate on the adsorbent as a function of its pressure (if gas) or concentration (if liquid)
at constant temperature
Aerobic oxidation Oxidation by air under ambient conditions
Aerocellulose Aerogels made from cellulose
Aeroclay Aeroclays are clay-based aerogels generally elaborated by freeze-drying of
clay-based hydrogels (for example, gels prepared with sodium-exchanged montmorillonite
clay). It is accepted that the freeze-drying step results in a rearrangement of clay sheets to
create the lightweight, oriented and porous structure of the final clay-based aerogel
Aerocore An organic monolithic panel manufactured by American Aerogel Corporation
Aerogels Defined by IUPAC as “Gels comprised of a microporous solid in which the
dispersed phase is a gas” [see Pure Appl. Chem. 79(10):1801–1809, 2007]. However, the
definition retained in this handbook is the one by Kistler, as “gels in which the liquid has
been replaced by air, with very moderate shrinkage of the solid network”
Aerogel functionalization Implementation of functional groups into aerogels
AeroSand Sand bonded by aerogels
M.A. Aegerter et al. (eds.), Aerogels Handbook, Advances in Sol-Gel Derived
Materials and Technologies, DOI 10.1007/978-1-4419-7589-8,# Springer Science+Business Media, LLC 2011
893
Aerosculpture Word invented by the author I. Michaloudis, from air and sculpture. A pair
of parenthesis – as a personal symbol of an open “space in between” – replaces the letter o
and gives the visual word aer( )sculptureAerosol Suspension of colloidal solid particles or liquid droplets in a gas, such as air
AFM Atomic force microscopy
Ageing (or Aging) Experiment where a material is maintained for a certain time in
constant environment conditions and its characteristics are slowly changing with time.
Specifically speaking with gels, ageing is a curing period where gels are immerged in a
specific liquid media where ageing mechanisms (generally, syneresis and/or Ostwald
ripening) are promoted or frozen
AIBN Azobisisobutyronitrile
Alcogel A wet gel containing alcohol formed by sol-gel method
ALD Atomic layer deposition
Alkoxide Sol-gel precursor of chemical formula M(OR)n, where M designates a cation,
R an alkyl group and OR an alkoxide group. Alkoxides are often available, in a more or
less polymerized form, in solution in their parent alcohol (for example ethanol for TEOS
or methanol for TMOS)
Allophane Allophane is an amorphous clay from natural soil; it is a natural alumino-
silicate originating from the transformation of volcanic ashes and glasses with weathering.
Allophane exists for young volcanic soil and is progressively transformed into crystalline
clays, halloysite, then into kaolinite
Ambigels Gels dried by evaporation of their liquid with moderate shrinkage. Ambigels
are considered as “aerogels” and sometimes termed “ambient pressure drying aerogels,”
when their shrinkage is moderate and their specific pore volume high
Ambient pressure drying Drying of gels by evaporation of their liquid with moderate
shrinkage in room temperature and pressure conditions
Amorphous material An “amorphous material” is a solid in which there is no long-range
order of the positions of the atoms
AN Ammonium nitrate
Analyte The chemical species being analyzed
Anaphylatoxins A toxic substance formed in the blood that is associated with bacterial
polysaccharides
Anthropogenic A process that results from human activity
AP Aerogel powder and/or particles
APD Ambient pressure drying. See also Ambigels
Apparent thermal conductivity Thermal conductivity value assigned to a material that
exhibits thermal transmission by at least one nondiffusive mode of heat transfer resulting in
property variation with specimen thickness, or surface emittance
APTES 3-Aminopropyltriethoxysilane
Arrhenius law Expression describing the exponential dependence of a reaction on an
activation energy
ASCE Alcohol supercritical extraction
ASTM American Society for Testing and Materials
Attenuation length L (optical) The distance traveled across in an aerogel, where the
probability that a photon has not been absorbed has dropped by 1/e (where e ¼ 2.71828)
AZC Aerogel sulfated zirconia doped with cerium
AZS Aerogel sulfated zirconia
AZSCr Aerogel sulfated zirconia doped with chromium
894 Glossary, Acronyms and Abbreviations
B
BCAM Base-catalyzed, acid-modified
bcc Body centered cubic structure
Bending strength Strength of a material tested in a bending test most often using
rectangular bars supported by two racks separated by a fixed distance. A bar is subjected
in the middle by a force and bends thereby. The fracture strength is calculated from the
maximum force and the geometry of the test bar
BESS Balloon-borne experiment with a superconducting spectrometer
BET Evaluation method named after Brunauer, Emmett, and Teller to obtain the surface
area from adsorption isotherms due to a theory for multilayer adsorption
BF Bright field
Binder A material bonding together e.g., sand grains, very often a polymer or colloidal
sodium silicate
Biomimicry From bios, meaning life, and mimesis, meaning to imitate: It is an ancient
concept recently returning to scientific thought that examines nature, its models, systems,
processes, and elements – and emulates or takes inspiration from them to solve human
problems sustainably. Scientific and engineering literature often uses the term biomimeticsfor the process of understanding and applying biological principles to human designs
Biosensor see “Sensors (biochemical)”
BJH Barret, Joyner, and Halenda who developed a methodology to determine the pore
volume distribution from nitrogen adsorption isotherms using the Kelvin equation, relating
the capillary pressure to pore size via the interfacial tension of a fluid condensing in a
capillary
BMH Born–Mayer–Huggins model for silicon dioxide, an empirical potential consisting
of pairwise-additive repulsive terms and Coulombic interactions
BO Bridging oxygen
Bolus release Administration of a drug over a relatively quick amount of time (less than
5 min) in comparison to a sustained delivery which can last over hours
Bonding bridge Bridge between two sand grains made up by a polymer or an aerogel
Br€onsted acidity Chemical compound presenting Br€onsted acid sites that are able to lose
a proton
Bridgman furnace A furnace with at least three zones being at different temperatures.
A hot zone and a cold zone are separated by an adiabatic zone. Directional solidification
or crystal growth is achieved by either pulling the sample through the furnace from hot to
cold or by moving the furnace
Brittle fracture Fracture of a material being completely elastically stressed (no irreversible
plastic deformation)
BSA Bovine serum albumin
BSE Backscattered electrons
BTAC Benzyltrimethylammoniumchloride
BTMSH 1,6-Bis(trimethoxysilyl)hexane
BTMSPA Bis(trimethoxysilyl-propyl) amine
Bulk-modified Sol–gel material prepared by adding probe to the precursor mixture (also
known as predoped)
C
C3a A plasma inflammation marker (plasma anaphylatoxin generation) which is part of the
complement pathway.C3a is the released degradationproduct ofC3 (complement component 3)
Glossary, Acronyms and Abbreviations 895
C5a A plasma inflammation marker (plasma anaphylatoxin generation) which is part
of the complement pathway. C5a is the released degradation product of C5 (complement
component 5)
Capillary Tube of small internal diameter, typically of the order of a few mm or less, in
which liquids can raise spontaneously, when one end of the tube is dipped in these liquids
Capillary stresses Mechanical stresses due to surface interaction of a liquid with a
capillary and the presence of a gas–liquid meniscus in a capillary pore, responsible for the
liquid raise in such capillary
Carbon aerogel Aerogel obtained by pyrolysis of an organic (polymeric) aerogel under
protective atmosphere
Carbon AeroSand Sand bonded by carbon aerogels
Carman–Kozeny equation This equation is empirical and relates the permeability
to the pore size and pore volume:D ¼ ð1� rrÞrw2=4Kwwhere rr is the relative density,
rw is the hydraulic radius and Kw is the so-called the Kozeny constant close to 5
CARS Coherent anti-Stokes Raman scattering
Cavitation Creation of cavities within a liquid or solid caused by the propagation of a
pressure wave through this liquid or solid. It may also mean the formation of vaporous
bubbles in a liquid due to a transient pressure drop below its vapor pressure
Cellulose acetate Salt of acetic acid with cellulose
Cellulose carbamate Carbamates are esters of the carbamic acid NH2COOH. A salt made
from cellulose and urethanes (an amine bonded to any organic radical R)
Cerenkov counter see Cherenkov counter
Chalcogel A gel composed of a metal chalcogenide framework
Chalcogenide aerogel Aerogel composed of metal chalcogenide frameworks
Chemical gel According to the definition given by Flory PJ [(1974) Gels and gelling
processes. Disc. Faraday 57:7–18], these gels are polymeric gels that present, on the contrary
of physical gels, a cohesive structure governed by the presence of covalent bounds
Cherenkov (or Cerenkov) counter Photo counters which permit to identify electrically
charged particles in high-energy physics experiments, from their radiative properties
when traveling across a transparent material with a refractive index close to 1 (e.g., an
aerogel)
Chitosan A polysaccharide derived from chitin
Chy a-Chymotrypsin
Classic or conventional gel Gel obtained by hydrolysis and polycondesention of alkox-
ides in the presence of a common precursor and solvent (alkoxide and water)
Chlordecone Chlordecone is a very though pesticide (C10 Cl10 0) which was used in
Africa, Central America and West Indies mainly for the protection of banana plantation.
Chlordecone induces cumulative and delayed toxicity
CD-62P P-selectin, a cell adhesion molecule found on active platelet cell membranes
CL-20 Energetic materials lexicon for 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaiso-
wurtzitane, a powerful chemical explosive
cN/tex The unit Centi Newton per tex
Cogelation Gelation in the same sol or polymer solution of, at least, two interconnected
solid networks due to the presence in this sol of the corresponding precursors and catalysts
Coke Carbonaceous solid deposed on the surface of the solid catalyst
COLD supercritical drying The use of supercritical CO2, with a critical temperature of
31�C, for aerogel formation. This is in contrast to hot supercritical drying employing
alcohols, where high temperatures are required to achieve a supercritical state
896 Glossary, Acronyms and Abbreviations
Collapsibility Ability of a core or mould material to be disintegrated (mechanically,
thermally, by vibration or oxidation)
Colloidal-type aerogel Gel obtained by gelation of colloidal particles. Aerogels adopting
a morphology characterized by spherical nanoparticle components
Compactibility The ability of a sand-binder mixture to become dense homogeneously
Compression Pack™ An insulation system based on Cabot Nanogel® in a pre-packaged
form commonly used to insulate tubing and pipe systems such as oil pipelines
Compressive strength The maximum compressive stress (Force per unit cross section
area) a material can withstand without failure
Condensation In oxide aerogels, a chemical transformation which consists in linking two
precursor molecules, one of which at least has been hydrolyzed, to build a M–O–M or a M–
(OH)–M bridge by elimination of a H2O or an alcohol ROH molecule. In organic aerogels,
strong –(C–C)– covalent bonds are established between two organic sol–gel precursor
molecules, by elimination of another smaller organic molecule. In chalcogenide aerogels,
metal–chalcogenide bridges form by release of H2S when preceded by thiolysis; alterna-
tively, metal chalcogenide particles are linked together under oxidative conditions where the
nature of the bonding is yet to be determined
Conductimetric Related to measurement of solution conductivity
Confined mold A closed, fixed volume sample well used in RSCE processing
Contact angle Angle between a droplet of liquid and a flat surface
Coprecursor technique or method Method used to make hydrophobic aerogels through
incorporation of an additional silane reagent to sol–gel recipe
Core Positive image of a cavity in cast pieces of metal
Core–Shell aerogel Aerogel comprising of core–shell nanoparticles i.e., nanoparticles
that have two separate chemical components, one that makes up the inside (core), and one
that deposits on the outside (shell)
COSMO “Conductor-like screening model,” in which a molecule is embedded in a
continuum dielectric meant to represent the surrounding solvent
Cross-linker A molecule being able to link cellulose polymer chains chemically together,
replacing the hydrogen bonds by stronger covalent bonds. For chalcogenide aerogels formed
from Zintl ions, the cross-linker is a Pt2+ ion that forms a covalent linkage between
chalcogenide clusters
Crucible Hollow body in which a metal is molten
Cryogel Gel dried by rapid freezing and sublimation of its solidified solvent. A cryogel is
considered as an “aerogel” when its shrinkage is moderate and its specific pore volume high
CS Thermal insulation cylinders and special-shaped parts
CSCE CO2 supercritical extraction
CSH Combined solvent exchange and hydrophobization
C/T Molar ratio between the cellulosic repeat units and TDI
CTAC Cetyltrimethylammoniumchloride
CVD Chemical vapor deposition
cyt c Cytochrome c
Cytotoxicity A quantification of the products that may have a toxic effect on cells
Drug carriers Materials loaded with pharmaceutical compounds
Dry strength Strength of the fully hardened sand-binder mixture
DTA Differential thermal analysis
Dtex Unit to measure the density of fibers, defined as the mass in grams per 1,000 m.
Dtex ¼ decitex ¼ mass per 10,000 m
Dulong–Petit law A chemical law proposed in 1819 by French physicists and chemists
Pierre Louis Dulong and Alexis Therese Petit stating the classical expression for the specific
898 Glossary, Acronyms and Abbreviations
heat capacity of a crystal due to its lattice vibrations; the specific heat equals 3 R/M,
corresponding to the high temperature limit of the specific heat. R is the gas constant and
M is the molar mass
Dyad Two individual units that work together as a pair
Dynamic hot-wire method It allows to determine the thermal conductivity by embedding
a wire into the material to be investigated. The wire deals as heating element and tempera-
ture sensor at the same time and is heated with a constant heat power. From the time-
dependent temperature increase of the wire the thermal conductivity is derived
E
E Young’s modulus (E). It is, within the limits of elasticity, the ratio of the linear stress
(force to which a solid rod is submitted, divided by its cross section area) to the linear strain
(relative elongation or contraction of the rod)
ecoating Emissivity of a coated glass surface
eglass Emissivity of a glass surface
EACAC Ethylacetoacetate
EDL Entry, descent, and landing
EDLC Electrochemical double-layer-capacitor
EDX Energy dispersive X-ray spectroscopy, a common spectroscopy technique available
on many electron microscopes
EELS Electron energy loss spectroscopy, a common spectroscopy technique available on
many electron microscopes
Effective total thermal conductivity Thermal conductivity of a material that exhibits
thermal transmission by several modes of diffusive heat transfer
EFTEM Elemental transmission electron microscopy
Elastic modulus see Young’s modulus
Elastomer Thermoplastic or thermoset polymer that can stretch by a large extent and then
return to its original shape without permanent deformation. Elastomers are only slightly
cross-linked
Electret Dielectric material which presents a quasi permanent electric dipole
EM Energetic material or electron microscopy
EPS Expanded Polystyrene, a commonly used, inexpensive polymer based insulation.
Made from polystyrene beads which are loaded with a solvent such as pentane and then
allowed to expand at elevated temperature to produce foam insulation
Esterification A reaction of an alcohol ROH (R: organic group) with an acid HA
(A: anionic group) to produce an ester ROA and water H2O
ESR Electron spin resonance
Et3N Triethylamine
Ethanol Ethyl alcohol (C2H5OH)
ETA Emanation thermal analysis
etac Ethyl acetate
EVA Extravehicular activity
EW ratio Ratio between the amine equivalent weight of hydrogen and the isocyanate
EXAFS Extended X-ray absorption fine structure, i.e., the fine structure present in the
X-ray absorption spectra beyond the absorption edge
Glossary, Acronyms and Abbreviations 899
F
F Formaldehyde
F-aerogel Aerogel obtained after a freeze drying process
fcc Face centered cubic structure
FEM Finite-Element Modeling, a computational technique for determining the mechanical
properties of objects
Fibril A thin fiber of cellulose in which the polymer chains are arranged like filaments in
a rope. Macrofibrils have a diameter of around of 60–400 nm, microfibrils of around 20–
30 nm, elementary fibrils 3–10 nm
Fineness Surface roughness of a sand mould or core
Fischer–Tropsch synthesis reaction Is a catalyzed chemical reaction in which synthesis
gas, a mixture of carbon monoxide and hydrogen, is converted into liquid hydrocarbons of
various forms
Flowability There are two types of flowability. One is the ability of a sand binder mixture
to be fluidized by pressurized air and thus can be shot into a form to yield a core; the second
one means that the sand-binder mixture trickles easily into a form
FM Flexible thermal insulation felt
Foam A solid or liquid matrix containing macropores or gas bubbles
Formate species Methanoate species or ion CHOO�
Fourier transformed infra red spectroscopy (FTIR) Measurement technique whereby
infra-red absorption spectra of materials are analyzed by mathematical Fourier transform
methods
4-methylpenta2-ol C6H14O
Fractal dimension In gel networks or aggregates of nanoparticles in which the mass Minside any sphere of radius R, about a centre chosen at random in the gel network or
aggregate, increases statistically with R as M � Rf, the number f is usually a noninteger
and is termed the fractal dimension. Aerogels are examples of fractal solids
Fractional function of the first kind f0�L(T) Fraction of the total black-body radiation
intensity having wavelengths between 0 and LFracton A collective quantized vibration on a substrate with a fractal structure
Free-dimensional space art The author I. Michaloudis is playing with the “three-
dimensional” space which in the case of the indefinitive transparency of his aer( )
sculptures becomes a non-Euclidean space. Silica aerogel itself can be considered as a
personification of what the French mathematician Henri Poincarre named a “representative
space,” a space you cannot measure; you just live in with all your senses; for more
information see Ioannis MICHALOU(di)S, “Aer( )sculpture: the enigmatic beauty of
aerogel’s nonentity in a pilot art and science project,” Journal of Non-Crystalline Solids
(2004) 350:61–66
Freeze drying Drying of a wet sample along the sublimation curve of the solvent. The
process avoids the direct liquid–gas transition observed in ordinary drying
FTIR Fourier transform infrared spectroscopy
Functionalization Chemical action consisting in functionalizing (adding functional
chemical groups) a molecule or the surface of a solid, by chemical synthesis or grafting
methods
FW Formula weight
900 Glossary, Acronyms and Abbreviations
G
Gas permeability The gas flow velocity through a porous body is proportional to the
pressure gradient applied across it. The constant of proportionality between gas flow
velocity and pressure gradient is the permeability and thus a measure of the resistance a
porous body exerts against gas flow through it
Gel point This is the state of condensation of a precursor or of suspended nanoparticles,
in a liquid, where gelation is first observed
Gelation Transformation of a liquid polymer solution or colloidal suspension (a sol) to a
solid impregnated with liquid, by continuous formation of an open and porous three-
dimensional polymer, uniformly throughout the entire solvent, without any formation of a
precipitate
GHSV Gas hourly space velocity; it is used for gaseous feed stream with the volumetric
flow rate expressed in term of volume per hours, thus GHSV has units per hour
Glassy state A dense monolithic amorphous solid state in which the atoms or molecules
are not arranged in any regular order, as in a crystal, and which crystallizes only after an
extremely long time
g/Nm3 Unit meaning grams per normal cubic meter; Nm3 is the gas volume, in cubic
meter, at 0�C and 760 mm Hg
Goniometer Instrument used to measure contact angles
Gordian Task A task of epic proportions, of great difficulty, named after the Gordian knot
which in Ancient times posed an unsolvable challenge
Gradient density aerogel Aerogel with a continuously changing density profile
Grafting Chemical grafting is a chemical technique to permanently bond some chemical
moieties or molecules, onto a solid surface or another macromolecule
Graphene Monolayer of carbon atoms in a hexagonal arrangement
Green strength Strength of a sand-binder mixture directly after for instance core shooting
or manual compaction allowing to handle the sand mould or core without any waiting time
for hardening to occur
Griffith criterion The Griffith criterion states that the fracture strength of a brittle solid is
solely determined by its elastic properties, its surface tension and the crack or flaw size being
in the material
H
he External heat transfer
hi Internal heat transfer
ht Heat transfer in a cavity
HDI Hexamethylene di-isocyanate
Heck coupling Catalytic formation of a substituted alkene starting from an unsaturated
halide and an alkene (also called Mizoroki–Heck reaction)
Helium pycnometry Characterization method permitting to determine the skeletal
density and specific volume of a porous sample by measuring the pressure change of helium
in a calibrated volume
HEMA Hydroxyethyl methacrylate
Hemicellulose A blend of several polysaccharides, like cellulose, xylose, galactose,
mannose, and other glucoses
Hemolysis The breakdown of red blood cells with the release of hemo-globin
Glossary, Acronyms and Abbreviations 901
Heritage RTG (Radioisotope Thermoelectric Generator) Thermoelectric generators used
over the past several decades employing radioisotope heat sources
HPLC High pressure liquid chromatography
HMDI Bis(4-isocyanatocyclohexyl)methane
HMDS HexaMethylDiSilazane (CH3)3Si–(NH)–Si(CH3)3Hot crack Crack appearing during solidification in a casting
Hot disk method (or technique) A well-known transient plane method used to charac-
terizes both thermal conductivity and thermal diffusivity of materials. It is based on the use
of a hot-disk probe. In some publications, in honour of the inventor of the technique, it is also
referred to as “the Gustafsson probe” method
HOT supercritical drying High temperature supercritical drying process, at temperatures
>260�C, in an alcohol
Hot tearing Fracturing of a material at high temperature
HREM High resolution electron microscopy
HVAC Heating, Ventilation and Air Conditioning. It is the main source of energy
consumption in a building
Hybrid aerogel Aerogel with a solid network constituted of mixed organic and inorganic
(often silica) moieties
Hydraulic hotpress Machine used to seal and heat confined mold in RSCE processing
Hydrolysis Chemical transformation of a sol-gel precursor, which consists in replacing a
ligand OR (in an alkoxide) or OH2 (in a hydrated metal salt), by an OH ligand
Hydrophilic aerogel Aerogel for which the contact angle of a water droplet with the
porous external surface is <90� (i.e., water attracting)Hydrophilicity Ability of a material to be wetted by water
Hydrophobic aerogel Aerogel for which the contact angle of a water droplet on a porous
external surface is >90� (i.e., water repelling)Hydrophobicity Literally, “water-hating.” Ability of a material which cannot be wetted
by water; they are usually terminated with nonpolar organics
Hydroxyl –OH terminal group
High-performance insulation A common synonym for superinsulation. Materials and/
or systems with superior thermal insulation performance when compared with conventional
ones
Hygroscopy The ability of a material to attract and absorb water from the environment
(moisture, humidity)
Hyper velocity particle capture The capture of high velocity (>1 km/s), micrometer
scale particles in a porous material
I
I Luminescence intensity at a given concentration of quencher
I0 Luminescence intensity in the absence of quencher
ICF An “Inertial confinement Fusion” experiment in which the fluid submitted to nuclear
fusion experiments (deuterium and tritium) is confined inside the pores of carbon or silica
aerogels
IEEE Institute of Electrical and Electronics Engineers
IEMA Isocyanatoethyl Methacrylate
IGU Insulating glass unit
902 Glossary, Acronyms and Abbreviations
Impact strength Strength measured during an impact test as e.g., using a pendulum
hammer falling onto a prenotched sample from a certain height. After passing the sample
and fracturing it, the hammer has lost kinetic energy that is easy to measure. This loss is
the energy absorbed by the material upon fracture and called the impact strength. The same
approach can be taken for films by measuring the potential energy of a ball falling onto a
sample need to crack it (height variation at constant weight)
IP A thermal insulation panel
IPA Isopropyl alcohol
Ionic liquid Any salt that has a relatively low melting point. Ionic liquids can be used as
solvents when water or traditional organic solvents cannot be used
IR Infra red
IRVE Inflatable reentry vehicle experiment
K
K Bulk modulus (K) of a substance that measures the substance’s resistance to uniform
compression. It is defined as the pressure increase dP, needed to cause a given relative
decrease in dV/V (with dV <0). It is defined as K ¼ �dPdV
VKEK High Energy Accelerator Research Organization (in Japan)
Kelvin probe Probe used to measure the contact potential difference between tow materi-
als by Kelvin method
KHgd Ratio of the ppm adsorbed Hg2+ per gram adsorbent over the ppm Hg2+ remaining per
mL solution
KLM Krimholtz–Leedom–Matthaei equivalent circuit
Knudsen number (Kn) Dimensionless number defined as the ratio of the mean free path
length of gas atoms/molecules to a representative physical length scale, e.g., pore size; the
number is named after Danish physicist Martin Knudsen (1871–1949)
KSV See Stern–Volmer quenching constant
L
LDMM Low density microcellular materials, a type of SPAM
Leach Removal of a soluble species from a sample due to washing with solvent
LED Light-emitting diode, an electronic light source
Lewis acid A chemical compound, A, presenting a site that can accept a pair of electrons
from a Lewis base, B, that acts as an electron-pair donor, forming an adduct
Lewis base Amolecule or ionwith a lone pair of electrons capable of acting as a donor to an
electron-deficient molecule or ion, such as a metal cation. Lewis bases can be classified as
hard or soft, depending on the extent of polarizability. Hard bases haveminimal polarizability
and form more thermodynamically stable complexes with compact metal ions, whereas soft
bases are more polarizable and form more stable complexes with large metal ions. Examples
are the F� anion and the O atom in water H2O
LIGA German acronym for LIthographie, Galvanoformung, Abformung (Lithography,
Electroplating and Molding); it is a technique used to produce high aspect ratio components.
In LIGA, selected regions of a polymer slab are cross-linked by exposure to collimated
X-rays. Unexposed regions are removed with suitable solvents, and metal is electrodeposited
Glossary, Acronyms and Abbreviations 903
in the voids. After electrodeposition the remaining polymer is removed and the metal mold is
used as a mold for polymer and ceramic components. Because of the large penetration of
X-rays within the polymer, aspect ratios can be achieved with the Liga method that are
otherwise not accessible to any other technique
Lignin Chemical compound derived from wood and plant cell walls. It is a complex bio-
polymer made of a network of furan and benzol rings with many OH andMeO groups attached
Lignocellulose Mixture of cellulose, hemicellulose and lignin
Live/dead cell cytotoxicity assay A measurement technique to quantify cell viability
though the amount of live and dead cells within the culture. Only live cells uptake calcein
which is hydrolyzed by intracellular esterases to fluoresce green. Only cells with a compro-
mised cell membrane (dead or dying cells) can uptake ethidium which binds to DNA to
fluoresce red
LLNL Lawrence Livermore National Laboratories
Lost formmould Mould made from a material being destroyed after casting (materials are
typically bonded sand, clays and gypsum)
LNG Liquid natural gas
LS Light scattering
Luminescence Emission of light, often following absorption of a photon
M
Macropores According to IUPAC convention, macropores are pores with a characteristic
size (e.g., diameter when meaningful) above 50 nm
Macroporous Material with pores than >50 nm
Martian crustal materials Ubiquitous, fine grained dust found on the surface of Mars
believed to consist of silicates, iron oxide, carbonates and clays
MAS-NMR Magic angle spinning-nuclear magnetic resonance
Maxwell–Garnet relation A theory by which a refractive index of nano-composite is
determined by the ratio of compositions
MCF Mesoporous cellular foams
Mercury porosimetry (or intrusion) Measurement of the specific porous volume and of
the pore size distribution function by applying a continuous increasing pressure on liquid
mercury such that an immersed or submerged porous solid is penetrated by mercury. If the
porous body can withstand the pressure without fracture the Washburn equation, relating
capillary pressure to capillary diameter allows converting the pressure penetration curves
into a size distribution curve. If a sample is contracted without mercury intrusion, a specific
mechanical model based on the buckling theory must be used
Mesopores According to IUPAC convention, mesopores are pores with a characteristic
size (e.g., diameter when meaningful) comprised between 2 and 50 nm
Mesoporous Material with pores with size in the 2–50 nm range
Metal Chalcogenide A material composed of metal cations and chalcogenide (sulfide,
selenide, or telluride) anions
Metal penetration Liquid metals can intrude into the open porous surface of a sand-
binder mixture. This penetration leads to casting defects. Metal penetration also means a
reaction occurring between the melt and an oxidic sand that can lead to the formation of
silicates
Metathesis reaction Partner switching
Methoxylation Reaction with methanol to convert Si–OH groups to Si–OCH3 groups
904 Glossary, Acronyms and Abbreviations
MF Melamine–formaldehyde aerogels
Micropores According to IUPAC convention, micropores are pores with a characteristic
size (e.g., diameter when meaningful) below 2 nm
Microporous Material with pores size in the 0.1–2 nm range
MLI Multilayer insulation
MMA Methylmethacrylate
Mould A body having a more or less complex geometrically shaped cavity in which a
liquid metal is cast and solidifies
MOR The Modulus of Rupture; it is the force per unit cross-section area, necessary to
break a given material bar supported flatwise at two points 1 ft apart. It is expressed by
18 times the load which is required to break a bar, when the loaded is applied in the middle
Non-intrusive mercury porosimetry Characterization technique to study the porous
texture of a material by collapsing this material under an isostatic mercury pressure, at
pressures low enough to not induce mercury intrusion in the pores
NOVA laser High-power laser built at the Lawrence Livermore National Laboratory
(USA) in 1984 which conducted advanced inertial confinement fusion (ICF) experiments
Glossary, Acronyms and Abbreviations 905
Nucleation center Local area where a particle of a new material phase is formed
Nucleophilic atom Atom holding a partial positive electronic charge d+
O
OIHM Organic–inorganic hybrid materials
OKAGEL High insulating day lighting aerogel developed by OKALUXGmbH (Germany)
Oleophilic Oil attracting
Oligomer A polymer that consists of two, three, or four monomers
Opacify To scatter visible or infrared radiation
Optical thickness A statistical measure of how often a photon with the mean free path lphtinteracts with the material within a given distance dOptical transmission Transmission of an optical signal by transfer of light
Optical transparency Optical property of a piece of matter to let a picture or design be
visible, eventually by projection on a screen, when light shines through it
Organosilane Derivative of an inorganic silane that contains one or more organic moieties
bonded to a central Si atom
Ormosil ORganically MOdified SILicates: hybrid silica aerogels obtained by gelation of a
solid network with functionalized silica precursors on which some specific organic moieties
have been grafted
Ostwald ripening Ageing evolution of particles in a liquid by dissolution re-precipitation,
where the smaller particle dissolve and re-precipitate on the larger ones
P
P Porosity
PAN Poly(acrylonitrile)
PDF Atomic pair distribution function obtained from the analysis of the Bragg and diffuse
scattering
PDMS Polydimethylsiloxane, a macromolecular silica precursor belonging to the Ormosil
precursors family and called polydimethyl siloxane
PDMS aerogel A composite between PDMS and a metal chalcogenide aerogel
PEG Polyethyleneglycol
Percolation theory Describes the formation of clusters defined by a random variation in
the degree of connectivity of the cluster elements
Permanent mould Mould made mainly from heat resistant steel that can be re-used many
times
Permeability (D) The rate of flow of a liquid or a gas through a porous material
PEM Proton exchange membrane
P-EW Panasonic Electric Works Co., Ltd
PF See Phenolic-furfural aerogels
Phe l-Phenylalanine
Phenolic-furfural (PF) aerogels Aerogel obtained by the base or acid catalyzed reaction
of phenol and formaldehyde following the sol-gel route
Photocatalytic Capable of catalyzing a reaction initiated by light absorption
Photoluminescence Emission of light following excitation due to absorption of a photon
RHU Radioisotope heat source. A heater that radiates heat that results from radioisotope
decay
RICH counter A ring imaging Cerenkov counter. When a high energy physics particles
travels inside an aerogel, a radiation is emitted in a direction located on a cone which
is observable as a ring
RLA Reaction-limited aggregation, an aggregation model similar to DLA, except with a
finite probability of forming a bond upon contact between objects
RLCA Reaction-limited cluster aggregation, an aggregation model similar to DLCA,
except with a finite probability of forming a bond upon contact between objects
RSCE Rapid supercritical extraction method where the sol-gel precursors themselves
brought to a supercritical state inside a pressurized mould
RSL2 The (revised) Rahman–Stillinger–Lemberg model for water, consisting of hydrogen
and oxygen atoms interaction only through pair potentials
[Ru(bpy)3]+2 Tris(2,20-bipyridyl) ruthenium(II)
[Ru(dpp)3]+2 Tris(4,7-diphenyl-1,10-phenanthroline ruthenium (II)
S
S-aerogel An aerogel obtained after supercritical CO2 (l) extraction
Salt-Hydrate melt A concentrated solution of salts in water at higher temperature leading
to salt-hydrates like Ca(SCN)2.4H2O, LiClO4
.3H2O, ZnCl2.4H2O being mostly solid at
room temperature
SANS Small angle neutron scattering
SAS Small angle scattering
SAXS Small angle X-ray scattering
SBF Simulated body fluid. An acellular aqueous solution with inorganic ion composition
almost equal to human plasma
Scaffold A three dimensional structure that can be used to direct cell growth or serve as a
location for cell growth
SCAs Spherical carbon aerogels
Scattering General physical process where some forms of radiations, such as light, sound
or moving particles, are forced to deviate from a straight trajectory by one or more localized
nonuniformities in the medium through which they pass
Sc-CO2 Supercritical CO2
Sc-CO2 drying Supercritical drying of the gel performed by either substituting the solvent
present in the gel with liquid CO2 which is then taken to the supercritical state and removed,
Glossary, Acronyms and Abbreviations 909
or by directly using supercritical CO2 to remove the solvent. TC of CO2 is about 31�C, much
lower than the TC of common sol–gel solvents
SCD Supercritical drying
SCF Supercritical fluid
Sc-HT drying Supercritical drying of the gel performed by removing the solvent present
in the gel after taking it to the supercritical state, i.e., at temperature higher than the critical
temperature TC and pressure higher than the critical pressure PC
SEM Scanning electronic microscopy or microscope
SEM-FEG Field emission gun scanning electron microscopy
Semitransparent material Material partially transparent for thermal radiation in certain
wavelength regions; the results of its measurement concerning the radiative heat transfer are
influenced by the surface emittance of the boundaries
Sensor (chemical or biochemical) Device that measure a physical characteristics linked
to the concentration of a chemical or biochemical and converts it into a signal which can be
read by an observer or by an instrument
SERS Surface-enhanced raman scattering or Surface-enhanced raman spectroscopy
Shock impedance The total reaction of a medium to the transmission of shock wave
through it, expressed as the ratio of shock pressure to particle velocity at a given point in
the medium
SHPB Split Hopkinson Pressure Bar29Si-NMR Nuclear magnetic resonance of 29Si atoms
Silanol Hydroxyl terminal group bonded to a Si atom: �Si–OH
Silica Aerogel Aerogel obtained by hydrolyzation and condensation of a silicic alkoxide
Siloxane bridge Bond �Si–O–Si� between two Si atoms by the intermediate of one
oxygen atom
Silylation Method used to make hydrophobic aerogels via post gelation derivatization
with an additional silane compounds
SiOx Silica aerogels
SOFCs Solid oxide fuel cells
Solidification First order phase transformation, in which a liquid (melt) crystallizes
Sol–gel transition Transition of a colloidal solution into a solid network extending
through the whole sample space. The network is made up of the colloidal particles attached
to each other mechanically and might be bonded by various potentials. At the point of
contact so-called necks establish. The sol–gel transition might be considered as exactly that
point when a percolating net of particles (a cluster) spans through the wet fluid. See also
gelation
Solvent A liquid substance capable of dissolving other substances
Solvent exchange Replacement of one liquid in a solid–liquid mixture by another; a
solvent inside a wet gel is replaced by e.g., ethanol or carbon dioxide
Sonar system Sound navigation and ranging system
Sono-aerogel Aerogel obtained from sonogel
Sonochemistry Study of the effect of sonic waves and wave properties on chemical
systems
Sonication Method that applies ultrasound energy in a homogenenous or heterogeneous
system
Sonogel Gel obtained when the mixing of the precursor, solvent, and water is enhanced by
ultrasonic vibrations (sonication)
910 Glossary, Acronyms and Abbreviations
Sono-ormosil Ormosil prepared by a sonogel approach, also called “hard Ormosil.”
It incorporates an organic phase in the inorganic precursor sol in combination with
sonication of the precursors
Sonosol Sol resulting from applying ultrasound to an alkoxide–water mixture
SPAM Small pore area material, a foam with density of less than 1 g/cm3 and an average
pore area of less than 500 mm2 produced by American Aerogel Corporation
Specific surface area Surface area per unit volume of a material or per unit mass. Both are
convertible via the density of the material
SQUID Superconducting quantum interference device, a very sensitive magnetometer
sscm Standard cubic centimeters per minute
Stellar nucleosynthesis Nuclear reactions within a star that create elements with an
atomic number >1
STEM Scanning transmission electron microscopy
Stern–Volmer equation Plot of the intensity ratio in the absence and presence of
quencher (I0/I) as a function of quencher concentration; used as a calibration curve for
quenching-based sensors
Stern–Volmer quenching constant (KSV) Constant for a given quenching process; it is
the product of the bimolecular rate constant for the reaction of quencher and the luminescent
species and the luminescence lifetime in the absence of quencher
Stirling engine A technology that involves the adiabatic expansion and contraction of a
gas to move a piston as a result of a thermal gradient. The mechanical is typically converted
to electrical power through an alternator
Stochastic reconstruction A type of reconstruction in which limited experimental data
is used to generate a statistically representative model of a material
Strength See bonding-, impact-, tensile strength
Subcritical conditions Temperature T and pressure P conditions below the critical point
temperature Tc and pressure Pc of a fluid
Subcritical crack growth In a piece of solid material, a crack will begin to spontaneously
grow when the strain energy (plastic + elastic deformation) which is released during crack
growth is � the gain in surface energy. Subcritical crack growth relates to crack growth
below this critical limit, in particular by corrosion mechanisms
Subcritical drying Adrying process performed at a temperatureT and a pressureP below the
critical point temperatureTc and thepressurePc of thefluid contained in theporosity of thewetgel
Supercritical drying Drying of a wet gel by application of temperature–pressure
conditions beyond the critical point of the solvent (Tc, Pc in the P–T phase diagram)
avoiding thus liquid–gas interfaces in the pore space of the gel body. The interfacial
tension in capillaries of different pore radii would establish stress gradients in the wet gel
leading to rupture of the fragile network. The capillary stresses might reach values up to
a few MPa
Supercritical fluid Fluid brought at a temperature and a pressure beyond the critical
temperature Tc and pressure Pc
Superfluid A special phase of matter such as helium at temperatures below 2.18 K in
which, when cooled to temperatures near absolute zero, the molecules exhibit special
quantum effects. In the superfluid state, flow proceeds without any friction and the fluid
viscosity becomes zero
Superhydrophobic Surface on which a water droplet appears to sit without any significant
surface wetting and exhibits a contact angle in excess of 150�
Glossary, Acronyms and Abbreviations 911
Superhydrophobic aerogel Aerogel on which the contact angle of a water droplet with
the porous external surface is >150�
Superinsulation Insulation systems based on the use of superinsulating products and/or
components and/or materials. A superinsulating materials is commonly defined by a thermal
conductivity lower than the one of air (e.g., 0.025 W/m K in room conditions) and more
recently lower than 0.020 W/m K
Superparamagnetic behavior Magnetic behavior of superparamagnetic materials
Superparamagnetic materials Nanosized ferro-, antiferro-, or ferrimagnetic materials
below the magnetic ordering temperature, with a single magnetic moment directed up or
down on a preferential (anisotropy) axis. When the thermal energy is sufficient to overcome
the magnetic anisotropy energy barrier, the transition from blocked to superparamagnetic
regime is observed
Superparamagnetic relaxation Transition from blocked to superpara magnetic regime
Surfactant Substance changing the wetting behavior of a surface, generally lowering the
surface tension. Molecules with long alkyl chains capable of forming supramolecular
assemblies (e.g., micelles). The supramolecular assemblies can act as templates for the
formation of porous inorganic materials
S–V Stern–Volmer plot
SXRFM See Synchroton X-ray microprobe
Sylilation Operation which consists in grafting �Si–X hydrophobic functionalities, with
the help of silica precursor carrying such functionalities (e.g., trichloromethyl silane).
Generally, R is an alkyl (linear or branched) or a perfluoroalky chain (for example,
CH2C4F11) and X, an halogenide (–F, –Cl or –I) or an amine (–NH2) or an alkoxy
(–OCH3, –OC2H5 etc.) group
Synchrotron X-ray microprobe A technique involving synchrotron radiation to detect
elements in low (parts per million) concentrations (SXRFM)
Syneresis Exudation of part of the liquid component of a gel contained in its porosity,
which, when immersed in a liquid, shrinks homogenously while keeping its shape (e.g.,
cylindrical or conical . . .) under the continuation of the condensation reactions after the gel
point
T
Tank baffles Straight flat plates that run inside and along the straight side of vertically
oriented cylindrical tanks or vessels
t-amylalcohol 2-Methyl-2-butanol C5H12O
t-butanol tert-Butyl alcohol (CH3)3C–OH
T/C Inverse of C/T ratio
TDI Tolylene-2,4-diisocyanate
TEA Triethylamine
TEG Thermoelectric generator. A general term for describing an electrical generator that
generates heat from a heat source
TEM Transmission electronic microscopy
Template Molecule or surfactant that dictate the morphology of the resultant material,
often by moderating growth. For instance a DNA molecule can serves as a pattern for the
synthesis of another macromolecule such as RNA. Also any porous solid such as a porous
polymer that serves as a pattern to the synthesis of another or porous solid of a different
nature (e.g., silica)
912 Glossary, Acronyms and Abbreviations
Tensile strength The maximum tensile stress (Force per unit cross section area) a material
can withstand without failure
TEOS Tetraethyl orthosilicate Si(OC2H5)4, also termed silicon tetra ethoxysilane: a
common SiO2 sol–gel precursor
Tensile strength Strength measured in a tensile test. A long thin sheet of a material is
subjected to a force stretching the sample. In a diagram of force needed to pull the sample
against elongation typically a maximum is shown, which marks the point of tensile strength.
Several norms (DIN, ISO, and ASTM) are available defining details of such a test for any
type of materials
TEP Triethylphosphate
Texture Physical characteristics of a solid with respect to the size, shape, pore surface, and
arrangement of its solid parts
TG Thermogravimetry, a measurement of a sample’s weight during heating
tg Gelation time
TGA Thermogravimetric analysis
Thermal conductivity The thermal conductivity k is a characteristic property of a matter
(solid, liquid, or gas) indicating its ability to conduct heat. It is defined as k ¼ dQ
dt
1
A
1
dT=dxwhere, dQ is the heat quantity (in Joule) passing during the time dt, across an area A of a slice
of matter of thickness dx, when the temperature difference between both faces of the matter
slice is dT. It is the proportionality constant between the heat flux and the temperature
gradient across a sample. The unit in the International System is Wm�1 K�1
Thermal release Liberation of the compound from an aerogel matrix induced by heat
Thermal Wrap™ Nanogel thermal wrap is an insulating blanket based on Cabot’s
Nanogel™ material
Thermites Pyrotechnic composition comprising a metal nanopowder (e.g., Al) dispersed
in an oxide, such as an oxide aerogel
Thermography Imaging of a hot surface by an infrared sensitive camera
Thermoporometry (Thermoporosimetry) A calorimetric method for characterizing the
pore texture from the melting or freezing point depression of a liquid confined in a pore,
by reason of the added contribution of surface curvature to the phase-transition free energy
THF Tetrahydrofuran
Three-dimensional tensor of the thermal conductivity Tensor which, when multiplied
by the temperature gradient vector according to the rules of matrix multiplication, gives
the heat flux density vector, i.e., heat flux density and temperature gradient must not have
the same orientation, which is the case in media with an anisotropic thermal conductivity
Thiolate An organic molecule terminated with an S� functionality. An example is
4-fluorophenylthiolate, FC5H4S�
Thyolysis reaction Analogous to hydrolysis, thiolysis involves reaction of H2S, in lieu of
H2O, to form metal thiols, which subsequently condense to form metal sulfides
TMB Trimethylbenzene
TMCS Trimethylchlorosilane
TMOS Tetramethyl orthosilicate Si(OCH3)4, also named silicon tetra methoxysilane: a
common SiO2 sol–gel precursor
TMS Trimethylsilyl group
TMSA Trimethylsilyl modified silica aerogel
TMSPM 3-(Trimethoxysilyl)propyl methacrylate
Glossary, Acronyms and Abbreviations 913
TNB Ti(O–nC4H9)4Tortuosity A property of a packed column of particles that indicates the degree of
unevenness of the path followed by the solute molecule as it passes down the column. The
most mathematic method to estimate tortuosity t is the arc-chord ratio i.e., the ratio of
the length of the curve L to the distance between the ends of it C; t ¼ L/CTP Daylightning panels
TPR Temperature programmed reduction
TRAP6 Thrombin receptor agonist peptide 6, which contains residues 42–47 of the
thrombin receptor
TSET Total solar energy transmittance
Transesterification Reaction of exchange of the organic group R00 of an ester R00O–(CO)–Rwith the organic group R0 of an alcohol R0OH to produce another alcohol R00OH and another
ester R0O–(CO)–RTwo-step process Acid catalyzed hydrolysis followed by base catalyzed condensation of