News tagged with colloids
Researchers discover why atoms in solids show a preference for certain structures
(PhysOrg.com) -- Nature likes some symmetries, but dislikes others. Ordered solids often display a so-called 6-fold rotation symmetry. To achieve this kind of symmetry, the atoms in a plane surround themselves ...
Mar 30, 2010 |
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A golden bullet for cancer: Nanoparticles provide a targeted version of photothermal therapy for cancer
In a lecture he delivered in 1906, the German physician Paul Ehrlich coined the term Zuberkugel, or "magic bullet," as shorthand for a highly targeted medical treatment.
Nanotechnology / Bio & Medicine
Mar 12, 2010 |
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A water splitter with a double role
(PhysOrg.com) -- There is a lot of hope invested in hydrogen, but it also presents some problems. It is energy-rich, clean and, as a constituent of water, of almost unlimited availability. However, so far ...
Mar 09, 2009 |
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Physicists Find a World of Motion In the Mystery of Aging Glass
(PhysOrg.com) -- Physicists super-cooled a liquid into glass in order to observe the slowing of particles. It's a material that still perplexes researchers despite thousands of years of household and industrial use.
Sep 19, 2009 |
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Researchers Record First Real-Time Direct Observations of Nanocrystal Growth in Solution (w/ Video)
(PhysOrg.com) -- The veil is being lifted from the once unseen world of molecular activity. Not so long ago only the final products were visible and scientists were forced to gauge the processes behind those ...
Aug 07, 2009 |
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Boost for Methanol? New solid catalyst for the direct low-temperature oxidation of methane to methanol
(PhysOrg.com) -- As a possible energy source for fuel cells or a substitute for gasoline, methanol is increasingly drawing attention beyond its importance as a feedstock for chemical industry. It can be stored much more efficiently ...
Aug 21, 2009 |
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Particles magnetically 'click' to form superstructures
(Phys.org) -- Geomag, the popular children's toy, contains small metal spheres that can be magnetically connected with a click to build a variety of towers, bridges, and sculptures. In a new study, scientists ...
Apr 10, 2012 |
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C60 could form a new kind of gel
(PhysOrg.com) -- C60, the spherical carbon molecule also known as a buckminsterfullerene, has intrigued scientists for its unique properties and potential applications in nanotechnology and electronics. Now scient ...
Nanotechnology / Nanomaterials
Feb 17, 2011 |
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Triblock spheres provide a simple path to complex structures
University of Illinois materials scientists have developed a simple, generalizable technique to fabricate complex structures that assemble themselves.
Jan 19, 2011 |
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First opal-like crystals discovered in meteorite
Scientists have found opal-like crystals in the Tagish Lake meteorite, which fell to Earth in Canada in 2000. This is the first extraterrestrial discovery of these unusual crystals, which may have formed in the primordial ...
Aug 03, 2011 |
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Cosmology in a Petri dish
Scientists have found that micron-size particles which are trapped at fluid interfaces exhibit a collective dynamic that is subject to seemingly unrelated governing laws. These laws show a smooth transitioning ...
Jan 26, 2012 |
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Prof gets messages from space
(PhysOrg.com) -- Barbara Frisken received several messages from outer space this year on her answering machine.
Space & Earth / Space Exploration
Dec 08, 2009 |
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Materials scientists find better model for glass creation
(PhysOrg.com) -- Harvard materials scientists have come up with what they believe is a new way to model the formation of glasses, a type of amorphous solid that includes common window glass.
Nov 04, 2009 |
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Anti-malaria drug synthesized with the help of oxygen and light
The most effective anti-malaria drug can now be produced inexpensively and in large quantities. This means that it will be possible to provide medication for the 225 million malaria patients in developing ...
Jan 17, 2012 |
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Plant with 'eggbeater' testure inspires waterproof coating
A floating weed that clogs waterways around the world has at least one redeeming feature: It's inspired a high-tech waterproof coating intended for boats and submarines.
Nanotechnology / Nanomaterials
Nov 10, 2011 |
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Colloid
A colloid is a type of chemical mixture where one substance is dispersed evenly throughout another. The particles of the dispersed substance are only suspended in the mixture, unlike a solution, where they are completely dissolved within. This occurs because the particles in a colloid are larger than in a solution - small enough to be dispersed evenly and maintain a homogenous appearance, but large enough to scatter light and not dissolve. Because of this dispersal, some colloids have the appearance of solutions. A colloidal system consists of two separate phases: a dispersed phase (or internal phase) and a continuous phase (or dispersion medium). A colloidal system may be solid, liquid, or gaseous.
Many familiar substances are colloids, as shown in the chart below. As well as these naturally occurring colloids, modern chemical process industries utilise high shear mixing technology to create novel colloids.
The subsequent table compares particle(s) diameters of colloids, homogeneous and heterogeneous mixture:
Thus, colloid suspensions are intermediate between homogeneous and heterogeneous mixtures. They are sometimes classified as either "homogeneous" or "heterogeneous" based upon their appearance.
The dispersed-phase particles have a diameter of between approximately 5 and 200 nanometers. Such particles are normally invisible to an optical microscope, though their presence can be confirmed with the use of an ultramicroscope or an electron microscope. Homogeneous mixtures with a dispersed phase in this size range may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions, or hydrosols. The dispersed-phase particles or droplets are largely affected by the surface chemistry present in the colloid.
Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color.
Colloidal systems (also called colloidal solutions or colloidal suspensions) are the subject of interface and colloid science. This field of study was introduced in 1861 by Scottish scientist Thomas Graham.
For more information about Colloid, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
