Synthesis Of Aqueous Dispersions Of Cationic Polyacrylamide

The copolymers P(AM-DA), P(AM-DMC) and P(DADMAC) with differentcompositions and molecular weights were synthesized,and characterized by IR,1HNMR. Interactions between P(AM-DMC) and P(DADMAC) in salt solution werestudied. Equilibrium pseudoternary phase diagrams were also discussed with differentcompositions, molecular weights and salt concentration. The results showed that byincreasing the molecular weight of copolymer or salt concentration or by reducing thecationic fraction, the critical phase separation concentrations of copolymers decreased.P(DADMAC) could promote the phase separation of P(AM-DMC) in salt solution.Stable aqueous dispersions of P(AM-DMC) were prepared by thecopolymerization of the cationic monomer (2-methacryloyloxyethyl) trimethylammonium chloride(DMC) and acrylamide (AM) in inorganic salt solution withP(AM-DA) as dispersant and V50 as initiator. The particle shapes were determined bySEM, and the particle sizes and distributions were determined by laser gradinganalysis. The effects on dispersion polymerization, such as the construction andamount of dispersants, the composition and concentration of monomer, the categoriesand concentration of inorganic salts, the temperature of polymerization and theconcentration of initiator, were studied. From all these above, some aspects of thecopolymerization mechanisms were examined.Results showed that a stable dispersion had a lot to do with the construction andamount of dispersant, the categories and concentration of inorganic salts and thecomposition and concentration of monomers. The P(AM-DA) with cationic fraction40% and intrinsic viscosity 2~3dL/g was a proper dispersant in the aqueous dispersion,and ammonia sulfate-sodium sulfate mixture had a better effect on the dispersionpolymerization of P(AM-DMC). Increasing the amount of cationic monomer wouldadd the difficulty of dispersion polymerization and have a disadvantage of phaseseparation.Based on the calculation of conversion, the size and amount of particle in thedispersions, the process of nucleation of water-soluble dispersion polymerization wasa separation of polymer dead chains. The particle sizes were a little big, which werebetween 500 and 5000nm. The content and viscosity of the dispersion depended onthe polymer concentration in dispersed phase.