It depends on the reaction conditions. We do most of our precipitation polymerisations (with or without surfactant) at about 80°C. In this case e have good results with potassium peroxodisulfate or ammonium peroxodisulfate.

This works for acrylamides and also for styrene.

Need not to use couple of materials. You can use only Sod. Persulfate, its a cheep material.

Ammonium per sulphate and ascorbic acid pair more suitable at low temp.

Dear all, find the links below covering most features of emulsion polymerization. My Regards

https://link.springer.com/article/10.1007/s00396-002-0744-6

https://doi.org/10.1021/ma025695y

https://doi.org/10.1002/pola.23362

https://doi.org/10.1002/polc.5070720121

https://doi.org/10.5254/1.3547244

DOI: 10.5772/intechopen.72143

Hi;

The choice of the redox initiating system comes from a thorough knowledge of the reaction mechanisms involved in the process. Experiments have shown that water-soluble redox initiators that produce hydrophobic radicals are advantageous, particularly for the removal of residual monomer. The reason for this is that hydrophobic radicals can enter the polymer particles (where most of the residual monomer is located) much more easily than hydrophilic radicals, which must undergo a number of propagation steps before they become sufficiently hydrophobic to enter the polymer particle.

However, some redox initiator systems are less effective at reducing the residual monomer content than others. Some redox systems employing metal promoters have limited usefulness in the preparation of aqueous emulsion polymers and the control of residual monomer content. For example, the hydrogen peroxide-ferrous salt system catalyzes emulsion polymerisation by the addition of iron ions, but is not useful in the preparation of all aqueous emulsion polymers, particularly those in which the pH of the aqueous phase is above 7, as iron ions aggregate and precipitate at high pH. Since the efficiency of the redox system depends on the hydrophobicity of the radicals formed, the best choice is the tert-butyl hydroperoxide -Ascorbic acid system.

Please see the attached documents for further details.

With my best regards

I used potassium persulfate with high thermal decompostion