Colloidal Systems - Surface and Colloid Chemistry: Principles and Applications - page 158

Tail

Solid

Loop

Tail

Liquid

Loop

FIGure 7.9 State of a polymer at (a) solid or (b) liquid drop. The polymer may be in three
typical states: tail, loop, or coil (helix-coil).

When two colloids approach each other, the adsorbed polymers increase
repulsion.
If the polymers interact, the two colloids will exhibit increased repulsion as the
solvent molecules would push toward this area.
The polymers, after adsorption, change in conformation, and thus may
increase stability.

However, one needs to find the suitable polymer for a given colloidal system. A typi-
cal example as found in biology is the stabilization of milk.

7.5.2.1 other applications of the Zeta Potential
In various kinds of industrial production, materials need to be treated with charged
colloidal particles. In such systems, the value of the zeta-potential analyses are
needed to control production. For example, in paper, adhesive, and synthetic plastics,
colloidal clay can be used as filler. In oil drilling, clay colloidal suspensions are used.
The zeta potential is controlled so as to avoid clogging the pumping process in the oil
well. It has been found that, for instance, the viscosity of a clay suspension shows a
minimum when the zeta potential is changed (with the help of pH from 1 to 7) from
15 to 35 mV. Similar observations have been reported in coal slurry viscosity. The
viscosity was controlled by the zeta potential.

7.5.3 I n d u S T r I a l a p p l I c aT I o n S

Colloids are found to play an important role in many aspects of industrial products.
Therefore, there is much research devoted to the following aspects of colloids:

Production of well-defined colloidal products
Stability criteria of colloidal products
Disability criteria
New applications of novel colloidal preparations