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A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, [1] while others extend the definition to include substances like aerosols and gels.
Unlike solutions and colloids, if left undisturbed for a prolonged period of time, the suspended particles will settle out of the mixture. Although suspensions are relatively simple to distinguish from solutions and colloids, it may be difficult to distinguish solutions from colloids since the particles dispersed in the medium may be too small ...
Polystyrene integrated solid foams are not commonly used in biomedical applications but have shown promise as a new drug delivery vehicle. The manipulation of the porous foam networks is a fundamental component in solid foam dosing – affecting variables such as dissolution, adsorption, and drug diffusion. [4]
[citation needed] In closed-cell foam, the gas forms discrete pockets, each completely surrounded by the solid material. In open-cell foam, gas pockets connect to each other. A bath sponge is an example of an open-cell foam: [not verified in body] water easily flows through the entire structure, displacing the air.
Complex fluids are mixtures that have a coexistence between two phases: solid–liquid (suspensions or solutions of macromolecules such as polymers), solid–gas , liquid–gas or liquid–liquid . They exhibit unusual mechanical responses to applied stress or strain due to the geometrical constraints that the phase coexistence imposes.
The term "emulsion" is also used to refer to the photo-sensitive side of photographic film. Such a photographic emulsion consists of silver halide colloidal particles dispersed in a gelatin matrix. Nuclear emulsions are similar to photographic emulsions, except that they are used in particle physics to detect high-energy elementary particles.
For a foam, these are a solid and a fluid, or a liquid and a gas. On larger scales both constituents are present in any region of the mixture, and in a well-mixed mixture in the same or only slightly varying concentrations.
Solid Dispersion medium Gas No such colloids are known. Helium and xenon are known to be immiscible under certain conditions. [74] [75] Liquid aerosol Examples: fog, clouds, condensation, mist, hair sprays: Solid aerosol Examples: smoke, ice cloud, atmospheric particulate matter: Liquid Foam Example: whipped cream, shaving cream, Gas vesicles