Self-stabilized dispersion polymerization

Another exciting new approach to the synthesis of defect-free PAn is self-stabilized dispersion polymerization (SSDP), recently reported by Lee and coworkers.84 In this process, aniline solution in aqueous HC1 was added to a chloroform-water mixture and stirred to give a cloudy colloid to which was added ammonium persulfate oxidant in HC1, producing the green ES product. The difference between SDDP and 

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Transfer constants of the macromonomers arc typically low (-0.5, Section 6.2.3.4) and it is necessary to use starved feed conditions to achieve low dispersities and to make block copolymers. Best results have been achieved using emulsion polymerization380 395 where rates of termination are lowered by compartmentalization effects. A one-pot process where macromonomers were made by catalytic chain transfer was developed.380" 95 Molecular weights up to 28000 that increase linearly with conversion as predicted by eq. 16, dispersities that decrease with conversion down to MJM< 1.3 and block purities >90% can be achieved.311 1 395 Surfactant-frcc emulsion polymerizations were made possible by use of a MAA macromonomer as the initial RAFT agent to create self-stabilizing lattices . 

The development of monofunctional precursors led to the production of graft copolymers that were fairly pure, in that they were relatively free from ungrafted polymer. Monofunctional precursors can also be made by condensation [3.66]. Indeed, graft copolymers made by the copolymerization of monomers with the reaction product of glycidyl methacrylate and the self-condensate of 12-hydroxys-tearic acid [3.67] have been used extensively in dispersion polymerizations, not only for technological applications, but also to study the mechanisms of dispersion polymerization and steric stabilization. 

The inverse emulsion form is made by emulsifying an aqueous monomer solution in a light hydrocarbon oil to form an oil-continuous emulsion stabilized by a surfactant system (21). This is polymerized to form an emulsion of aqueous polymer particle ranging in size from 1.0 to about 10 pm dispersed in oil. By addition of appropriate surfactants, the emulsion is made self-inverting, which means that when it is added to water with agitation, the oil is emulsified and the polymer goes into solution in a few minutes. Alternatively, a surfactant can be added to the water before addition of the inverse polymer emulsion (see Emulsions). 

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