Question

Discuss the way in which the addition of a polymer can modify the stability of a charge stabilized colloidal dispersion?

Answer 1

Stability is hindered by aggregation and sedimentation.Reducing the interfacial tension will
stabilize the colloidal system by reducing this driving force. When a colloidal particle,
immersed in solution, approaches an interface, which may be neutral or charged then
the charge effects plus the deformation of the colloidal ion atmosphere by the interface
lead to an effective interaction which can be attractive or repulsive, depending on various
factors like surface charge density etc. Remember any interaction will cause a change
in charge.

If the polymers are added to a charge stabilized collodial dispersionthey cover the
suspended particles there by preventing any attraction/repulsive interactions
between other particles/Ions present around a single colloidal particle.

Polymers have various functional groups, like carboxyl, hydroxyl, amine, and ester groups
These functional groups react with basic sites on the surface of each particle, binds & protects
the its surface of a particle in colloid thereby avoiding any interactions with surrounding
particles/ions, which may cause any modification in charge if polymers were not present/added.

In this way addition of polymer can modify the stability of a charged stabilized colloidal dispersion.

.