An upturned vial of hair gel

A gel (from the lat. gelu—freezing, cold, ice or gelatus—frozen, immobile) is an apparently solid, jelly-like material formed from a colloidal solution. By weight, gels are mostly liquid, yet they behave like solids due to the addition of a gelling agent. For other uses, see Latins and Latin (disambiguation). ... A Colloid or colloidal dispersion is a type of homogeneous mixture. ... Gelling agents are food additives used to thicken and stabilize various foods, like jellies, desserts and candies. ...

Composition

A solid network spans the volume of a liquid medium. Both by weight and volume, gels are mostly liquid in composition and thus exhibit densities similar to liquids. However, they have the structural coherence of a solid. The network can be composed of a wide variety of materials, including particles, polymers and proteins.

Cationic polymers

Cationic polymers are positively charged polymers. Their positive charges prevent the formation of coiled polymers. This allows them to contribute more to viscosity in their stretched state, because the stretched-out polymer takes up more space than a coiled polymer and thus resists the flow of solvent molecules around it. Cationic polymers are a main functional component of hair gel, because the positive charged polymers also bind the negatively charged amino acids on the surface of the keratin molecules in the hair. More complicated polymer formulas exist, e.g., a copolymer of vinylpyrrolidone, methacrylamide, and hydrogel N-vinylimidazole.^[1] For other uses, see Viscosity (disambiguation). ... This article is about the class of chemicals. ... Not to be confused with kerogen or carotene. ... A heteropolymer, also called a copolymer, is a polymer formed when two different types of monomer are linked in the same polymer chain. ...

Types of gels

Hydrogels

Hydrogel is a network of polymer chains that are water-insoluble, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are superabsorbent (they can contain over 99% water) natural or synthetic polymers. Hydrogels possess also a degree of flexibility very similar to natural tissue, due to their significant water content. A Colloid or colloidal dispersion is a type of homogeneous mixture. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ...

Common uses for hydrogels are

• currently used as scaffolds in tissue engineering. When used as scaffolds, hydrogels may contain human cells in order to repair tissue.
• environmentally sensitive hydrogels. These hydrogels have the ability to sense changes of pH, temperature, or the concentration of metabolite and release their load as result of such a change.
• as sustained-release delivery system
• provide absorption, desloughing and debriding capacities of necrotics and fibrotic tissue.
• hydrogels that are responsive to specific molecules, such as glucose or antigens can be used as biosensors as well as in DDS.
• In disposable diapers where they "capture" urine, or in sanitary napkins
• contact lenses (silicone hydrogels, polyacrylamides)
• medical electrodes using hydrogels composed of cross linked polymers (polyethylene oxide,polyAMPS and polyvinylpyrrolidone)
• Water gel explosives

Other, less common uses include A biosensor is a device for the detection of an analyte that combines a biological component with a physicochemical detector component. ... Baby cloth diaper filled with extra cloth. ... This article is about the urine of animals generally. ... Wingless type (left) and winged type (right) of disposable sanitary napkin. ... A pair of contact lenses, positioned with the concave side facing upward. ... Not to be confused with the element silicon. ... Polyacrylamide is an acrylate polymer formed from acrylamide subunits that is readily cross-linked. ... Vulcanization is an example of cross-linking. ... PolyAMPS, or poly(2-acrylamido-2-methyl-1-propanesulfonic acid), is an organic polymer. ... PVP (polyvinyl pyrrolidone, povidone, polyvidone) is a water-soluble polymer made from the monomer n-vinyl pyrrolidone: The monomer is carcinogenic and is extremely toxic to aquatic life. ...

• breast implants
• granules for holding soil moisture in arid areas
• dressings for healing of burn or other hard-to-heal wounds. Wound GEL are excellent for helping to create or maintain environment.
• reservoirs in topical drug delivery; particularly ionic drugs, delivered by iontophoresis (see ion exchange resin)

Common ingredients are e.g. polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with an abundance of hydrophilic groups. A breast implant is a prosthesis used to enlarge the size of a womans breasts (known as breast augmentation, breast enlargement, mammoplasty enlargement, augmentation mammoplasty or the common slang term boob job) for cosmetic reasons; to reconstruct the breast (e. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland For other uses, see Soil (disambiguation). ... For other uses, see Burn. ... Superficial bullet wounds In medicine, a wound is a type of physical trauma wherein the skin is torn, cut or punctured (an open wound), or where blunt force trauma causes a contusion (a closed wound). ... Iontophoresis is a non-invasive method of propelling high concentrations of a charged substance, normally medication or bioactive-agents, transdermally by repulsive electromotive force using a small electrical charge applied to an iontophoretic chamber containing a similarly charged active agent and its vehicle. ... Image:Example Ion exchange is a hockey players name resin. ... Chemical structure of polyvinyl alcohol Polyvinyl alcohol (PVOH, PVA, or PVAL) is a water-soluble synthetic polymer. ... Sodium polyacrylate also named acrylic sodium salt polymer or simply ASAP (repeating unit: -CH2-CH(CO2Na)- ) is a crosslinked acrylic acid polymer sodium salt, invented by Robert Niles Bashaw, Bobby Leroy Atkins and Billy Gene Harper in the Basic Research Laboratory of the Dow Chemical Company. ... Acrylate monomers are esters that contain vinyl groups, that is, two carbon atoms double bonded to each other, directly attached to the carbonyl carbon. ... A heteropolymer, also called a copolymer, is a polymer formed when two different types of monomer are linked in the same polymer chain. ... The adjective hydrophilic describes something that likes water (from Greek hydros = water; philos = friend). ...

Natural hydrogel materials are being investigated for tissue engineering, these materials include agarose, methylcellulose, hylaronan, and other naturally derived polymers.

Organogels

An organogel is a non-crystalline, non-glassy thermoreversible solid materials composed of a liquid organic phase entrapped in a structuring network. The liquid can be e.g. an organic solvent, a mineral oil or a vegetable oil. The solubility and particle dimensions of the structurant are important characteristics for the elastic properties and firmness of the organogel. Often, these systems are based on self-assembly of the structurant molecules^[2][3]. Crystallinity refers to the degree of structural order in a solid. ... This article is about the material. ... Look up material in Wiktionary, the free dictionary. ... For other uses, see Liquid (disambiguation). ... Methane is the simplest possible organic compound An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... Synthetic motor oil being poured. ... It has been suggested that this article or section be merged with cooking oil. ... Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... A particle is Look up Particle in Wiktionary, the free dictionary In particle physics, a basic unit of matter or energy. ... Elasticity has meanings in two different fields: In physics and mechanical engineering, the theory of elasticity describes how a solid object moves and deforms in response to external stress. ... Self-assembly is the fundamental principle which generates structural organization on all scales from molecules to galaxies. ...

Organogels have potential for use in a number of applications, such as in pharmaceuticals ^[4], cosmetics, art conservation^[5], and food^[6]. An example of formation of an undesired thermoreversible network is the occurrence of wax crystallization in crude oil ^[7]. Pharmaceutics is the discipline of pharmacy that deals with all facets of the process of turning a new chemical entity (NCE) into a medication able to be safely and effectively used by patients in the community. ... Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra – rock and elaion – oil or Latin oleum – oil ) or crude oil is a thick, dark brown or greenish liquid. ...

Xerogels

A xerogel ['zIrə,dʒεl] is a solid formed from a gel by drying with unhindered shrinkage. Xerogels usually retain high porosity (25%) and enormous surface area (150-900 m²/g), along with very small pore size (1-10 nm). When solvent removal occurs under hypercritical (supercritical) conditions, the network does not shrink and a highly porous, low-density material known as an aerogel is produced. Heat treatment of a xerogel at elevated temperature produces viscous sintering (shrinkage of the xerogel due to a small amount of viscous flow) and effectively transforms the porous gel into a dense glass. A pore, in general, is some form of opening, usually very small. ... For other uses, see Solvent (disambiguation). ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... A 2. ... This article or section does not cite its references or sources. ... This article is about the material. ...

Properties

Many gels display thixotropy - they become fluid when agitated, but resolidify when resting. In general, gels are apparently solid, jelly-like materials. By replacing the liquid with gas it is possible to prepare aerogels, materials with exceptional properties including very low density, high specific surface areas, and excellent thermal insulation properties. Thixotropy is the property of some non-newtonian pseudoplastic fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shear, the lower its viscosity. ... A 2. ...

Sound-induced gelation

The palladium complex is synthesised from palladium acetate and N,N'-Bis(salicylidene)pentamethylenediamine in boiling benzene and forms the anti conformer (left) and the syn conformer (right)

Sound induced gelation is described in 2005 ^[8] in an organopalladium compound that in solution transforms from a transparent liquid to an opaque gel upon application of a short burst (seconds) of ultrasound. Heating to above the so-called gelation temperature T_gel takes the gel back to the solution. The compound is a dinuclear palladium complex made from palladium acetate and a N,N'-Bis-salicylidene diamine. Both compounds react to form an anti conformer (gelling) and a syn conformer (non-gelling) which are separated by column chromatography. In the solution phase the dimer molecules are bent and self-locked by aromatic stacking interactions whereas in the gel phase the conformation is planar with interlocked aggregates. The anti conformer has planar chirality and both enantiomers were separated by chiral column chromatography. The (-) anti conformer has a specific rotation of -375° but is unable to gelate by itself. In the gel phase the dimer molecules form stacks of alternating (+) and (-) components. This process starts at the onset of the sonication and proceeds even without further sonication. Organopalladium chemistry is a branch of organometallic chemistry and deals with organic palladium compounds and their reactions. ... For other uses, see Ultrasound (disambiguation). ... For other uses, see Palladium (disambiguation). ... Cis-2-butene Trans-2-butene In chemistry, geometric isomerism or cis-trans isomerism is a form of stereoisomerism and describes the orientation of functional groups within the molecule. ... Column chromatography in chemistry is the preparative application of chromatography. ... Aromatic stacking interaction, sometimes called phenyl stacking, is a phenomenon in organic chemistry that affects aromatic compounds and functional groups. ... Planar chirality is a special case of chirality in which a molecule does not posess a asymmetric chiral carbon atom but perpendicular disymmetric planes due to restricted rotation around a chemical bond in the molecule. ... In chemistry, enantiomers (from the Greek ἐνάντιος, opposite, and μέρος, part or portion) are stereoisomers that are nonsuperimposable complete mirror images of each other, much as ones left and right hands are the same but opposite. ... Chiral column chromatography is a variant of column chromatography, where the stationary phase is chiral instead of achiral. ... The specific rotation of a chemical compound [α] is defined as the observed angle of optical rotation α when plane-polarized light is passed through a sample with a path length of 1 decimeter and a sample concentration of 1 gram per 1 millilitre. ...

Applications

Many substances can form gels when a suitable thickener or gelling agent is added to their formula. This approach is common in manufacture of wide range of products, from foods to paints, adhesives. Thickening agents, or thickeners, are substances which, when added to the mixture, increase its viscosity without substantially modifying its other properties, like eg. ... Gelling agents are food additives used to thicken and stabilize various foods, like jellies, desserts and candies. ...

In fiber optics communications, a soft gel resembling "hair gel" in viscosity is used to fill the plastic tubes containing the fibers. The main purpose of the gel is to prevent water intrusion if the buffer tube is breached, but the gel also buffers the fibers against mechanical damage when the tube is bent around corners during installation, or flexed. Additionally, the gel acts as a processing aid when the cable is being constructed, keeping the fibers central whist the tube material is extruded around it. Hair gel Hair gel is a hairstyling product that is used to stiffen hair into a particular hairstyle. ...

See also

• Aerogel
• Hydrocolloid
• Gel electrophoresis, Agarose gel electrophoresis, 2-D electrophoresis, SDS-PAGE
• Gel filtration chromatography, Gel permeation chromatography
• Paste (rheology)

A 2. ... Hydrocolloids are used in some skin care products A hydrocolloid is defined as a colloid system were the colloid particles are disperesed in water. ... Gel electrophoresis is a technique used for the separation of deoxyribonucleic acid, ribonucleic acid, or protein molecules using an electric current applied to a gel matrix. ... Digital image of 3 plasmid restriction digests run on a 1% w/v agarose gel, 3 Volts/cm, stained with ethidium bromide. ... Two dimensional gel electrophoresis, commonly abbreviated as 2-DE or 2-D electrophoresis, is a form of gel electrophoresis commonly used to analyze proteins. ... Picture of an SDS-PAGE. The molecular marker is in the left lane SDS-PAGE stands for Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis. ... Gel filtration chromatography is a laboratory technique to separate biomolecules by size. ... Gel permeation chromatography (GPC) also known as size exclusion chromatography (SEC) is a chromatographic method in which molecules are separated based on their size. ... This article is in need of attention. ...

References

The Journal of the American Chemical Society (usually abbreviated as , or JACS), is a peer-reviewed scientific journal, published since 1879 by the American Chemical Society. ...

External links

• Xerogel (definition)