Deflocculants

Deflocculants are chemical additives used to reduce flocculation and promote the dispersion of fine particles in suspensions. They act by adsorbing onto particle surfaces and imparting electrostatic repulsion or steric hindrance, or by disrupting interparticle bridges, a process sometimes called peptization. Consequently, the suspension remains fluid and stable against sedimentation or gelation.

Common deflocculants include sodium or ammonium polyacrylates, lignosulfonates, polycarboxylates, citrates, and silicates. Their specific performance depends on the particle system and the conditions of the suspension, such as pH and ionic strength.

Applications span multiple industries. In ceramics, deflocculants reduce slip viscosity and enable easy casting of ceramic suspensions. In paints and coatings, they stabilize pigment suspensions to prevent sedimentation and improve flow. In drilling fluids, they help disperse clay particles and control viscosity and gel strength. Deflocculants are also used in pharmaceuticals and cosmetics to maintain stable suspensions of active ingredients or pigments.

Limitations and considerations include sensitivity to pH and ionic strength, potential over-dispersion leading to excessively low viscosity or unstable suspensions, and compatibility with other formulation components. Proper dosage and testing are essential to balance stability, workability, and long-term performance in a given system.