The use of polyelectrolyte stabilisers for suspension polymerisation: the effect of pH on particle size distribution

Ammonium polymethacrylate (APMA) and sodium polymethacrylate (PMA‐Na) were used as suspending agents for the suspension polymerisation of methyl methacrylate (MMA). The effect of pH on particle sizes and the stabilisation mechanism were examined. Increasing the pH caused a decrease in the particle sizes, and the formation of fine particles with diameters smaller than 10 µm. The amount of suspending agent required to stabilise a monomer dispersion and to prevent coalescence during suspension polymerisation decreases with increasing pH. The prevailing stabilisation mechanism that governs the dispersion stability is probably the electrosteric mechanism.