I have used AIBN and benzoyl peroxide. AIBN was better for me.
Initial conversion for system initiated with KPS is higher than those initiated with BPO or AIBN. However, conversion reaches a constant value, thus the final conversion remains low (about 60%).
High initial polymerization rate and low final conversion in the presence of water-soluble initiator (KPS) may be attributed to the rapid decomposition of initiator in the aqueous phase where monomers exist.
When reaction was performed in the presence of BPO or AIBN, final conversion increased significantly and reached about 100%. However, polymerization rate in the presence of AIBN was higher than that of BPO, which can be attributed to the higher
decomposition rate constant of AIBN (9.8×10-6 s-1 at 60°C) in comparison with BPO (2.24×10-6 s-1 at 60°C).
Results of particle size analysis showed that although particle size is not affected by the oil-soluble initiator type, yet the particle size distribution (i.e., PDI) is dependent on the oil-soluble initiator type. When the reaction is performed in the presence of AIBN, particle size distribution (PDI) is narrow. This behaviour may be attributed to the rapid particle nucleation and growth as a result of rapid polymerization rate, resulting in the narrow particle size distribution.
When the water soluble initiator was used in the system, particle size decreased probably due to the low final reaction conversion.
Ref:
Barari M., Abdollahi M., Hemmati M., Synthesis and characterization of high molecular weight polyacrylamide nanoparticles by inverse-emulsion polymerization, Iran. Polym. J., 20, 65-76, 2011
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