Inverse emulsion polymerization of acrylamide and salts of acrylic acid

Abstract

Kinetics of the persulfate-initiated inverse emulsion polymerization of acrylamide and acrylic acid sodium and ammonium salt have been investigated. Rate orders with respect to the initiator, the monomers and the emulsifier were determined for all three monomers. Influences of the change of concentration of the individual components of the polymerization system on molecular weight and particle size of the resulting polymers were described. Overall activation energies of polymerizations were determined. Results of the kinetics measurements for the non-ionic acrylamide and the ionic salt of acrylic acid were compared. Dependence of the polymerization rate R p on the concentration of components in the polymerization system can be expressed for all three mononers by the following equation: R p = [ I] 0.5 [M] 1.5 [E] 0.1. These kinetic data are in good agreement with the supposed mechanism of polymerization. The almost sesquimolecular rate order with respect to the monomer proves to the participation of the monomer on the initiation reaction. This fact also explains the reason of the unusually low polymerization temperature of 40 °C. The persulfate-initiated inverse emulsion polymerization of acrylic monomers takes place as a solution polymerization in microparticles.