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When lyophilic sols are added to lyophobic sols, depending on their sizes, either lyophobic sol is adsorbed in the surface of lyophilic sol or lyophilic sol is adsorbed on the surface of lyophobic sol. The layer of the protective colloid prevents direct collision between the hydrophobic colloidal particles and thus prevents coagulation. [1]
In 1923, Peter Debye and Erich Hückel reported the first successful theory for the distribution of charges in ionic solutions. [7] The framework of linearized Debye–Hückel theory subsequently was applied to colloidal dispersions by S. Levine and G. P. Dube [8] [9] who found that charged colloidal particles should experience a strong medium-range repulsion and a weaker long-range attraction.
The gold number is the minimum weight (in milligrams) of a protective colloid/lyophilic colloid required to prevent the coagulation of 10 ml of a standard hydro gold sol when 1 ml of a 10% sodium chloride solution is added to it. [1]
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.
Particle agglomeration refers to the formation of assemblages in a suspension and represents a mechanism leading to the functional destabilization of colloidal systems. . During this process, particles dispersed in the liquid phase stick to each other, and spontaneously form irregular particle assemblages, flocs, or agglom
Examples are suspensions of rod-like viruses such as the tobacco mosaic virus as well as synthetic macromolecules, such as Li 2 Mo 6 Se 6 nanowire [9] or colloidal suspensions of non-spherical colloidal particles. [10] Cellulose and cellulose derivatives form lyotropic liquid crystal phases as do nanocrystalline (nanocellulose) suspensions. [11]
With grafted polymers, the backbone of the polymer chain is covalently bonded to the particle surface. Whereas an adsorbed polymer is a copolymer composed of lyophobic and lyophilic region, where the lyophobic region non-covalently adheres to the particle surface and the lyophilic region forms the steric boundary or spacer.
A sol is a colloidal suspension made out of tiny solid particles [1] in a continuous liquid medium. Sols are stable, so that they do not settle down when left undisturbed, and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. The size of the particles can vary from 1 nm - 100 nm.