Confined magnetic colloidal system for controllable fluid transport

Colloidal suspensions of microscopic particles show complex and interesting collective behaviors. In particular, the collective dynamics of colloids is fundamental and ubiquitous for materials assembly, robotic motion, microfluidic ...

What stops flows in glassy materials?

Glasses have a liquid-like disordered structure but solid-like mechanical properties. This leads to one of the central mysteries of glasses: Why don't they flow like liquids? This question is so important that it was selected ...

Scientists age quantum dots in a test tube

Researchers from MIPT and the RAS Institute of Problems of Chemical Physics have proposed a simple and convenient way to obtain arbitrarily sized quantum dots required for physical experiments via chemical aging. The study ...

Researchers develop method to create colloidal diamonds

The colloidal diamond has been a dream of researchers since the 1990s. These structures—stable, self-assembled formations of miniscule materials—have the potential to make light waves as useful as electrons in computing, ...

Having a ball: Crystallization in a sphere

Crystallization is the assembly of atoms or molecules into highly ordered solid crystals, which occurs in natural, biological, and artificial systems. However, crystallization in confined spaces, such as the formation of ...

Controlled dynamics of colloidal rods

Colloidal particles have become increasingly important for research as vehicles of biochemical agents. In future, it will be possible to study their behavior much more efficiently than before by placing them on a magnetized ...

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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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