Effect of hydrophilic macro-RAFT agent in surfactant-free emulsion polymerization

Here we report, synthesis of different molecular weight poly (styrene sulfonate) based macro-RAFT agents and their use as shell material in surfactant-free emulsion polymerization of styrene. Concentration and molecular weight of hydrophilic macro-RAFT agent has an influence on colloidal stability, particle size distribution and self-assembly. Microscopic and zeta-potential studies of colloids reveal that, the macro-RAFT agents used with low molecular weight (Mn = 1200) are comparable more efficient than high molecular weight (Mn = 46,800 and 116,000) for imparting narrow particle size distribution with good colloidal stability.

The use of hydrophilic macro-RAFT agent in surfactant free emulsion polymerization has many potential benefits. Efficiency of low molecular weight macro-RAFT agents with minimum charge on particle surface boosts the colloidal self-assembly. This method also provides the opportunity to functionalize the particle surface and control particle morphology. We have studied the effect of hydrophilic macro-RAFT agent on emulsion polymerization following the scheme depicted in figure below.Figure optionsDownload as PowerPoint slideHighlights
► Use of low molecular weight macro-RAFT agent helps colloid to self assemble.
► Size and dispersity of nanoparticles depends on macro-RAFT agents molecular weight.
► Method may provide the opportunity to control self-assembly.