Predicting the phase stability of soft matter

Soft matter is an important class of materials that typically consists of colloidal particles and/or polymers in a liquid medium. For certain compositions, these types of systems tend to (micro-)phase separate and unmix into ...

New route to build materials out of tiny particles

Researcher Laura Rossi and her group at TU Delft have found a new way to build synthetic materials out of tiny glass particles—so-called colloids. Together with their colleagues from Queen's University and the University ...

Glass transition meets Fickian-non-Gaussian Diffusion

Glass transition is a Grand Challenge in condensed matter physics and still reveals surprises, despite decades of intense research. For instance, diffusion in glassy liquids was until now thought to be qualitatively similar ...

A pathway to high-quality ZnSe quantum wires

One-dimensional semiconductor nanowires with strong quantum confinement effect—quantum wires (QWs)—are of great interest for applications in advanced optoelectronics and photochemical conversions. Beyond the state-of-the-art ...

Study reveals how to break symmetry in colloidal crystals

Nature keeps a few secrets. While plenty of structures with low symmetry are found in nature, scientists have been confined to high-symmetry designs when synthesizing colloidal crystals, a valuable type of nanomaterial used ...

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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.

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