during the synthesis of polymer/polymer core shell nanocomposites. we synthesize firstly the polymer through emulsion polymerization by the addition of monomer, initiator and the surfactant.. Now to prepare core shell insitu nanocomposites, we add the second monomer after the first polymer was synthesized. Now should we repeat the same conditions for second monomer: i mean in addition to initiator, should we add surfactant for the second time or it works as a catalyst and can work for the second monomer polymerization as well?
These mights be happened. Because the first monomer is already polymerized and you add another monomer, initiator in the same vessel. This may result s into mixture of two polymers.
For core shell composite the one of polymer must be hydrophilic and another one is hydrophobic so two distinct phase separeted during emulsion polymerization.
To my opinion and also reading, at the same time you can add all monomers to the emulsion. For example you should synthesise poly styrene with AA shell. You can add surfactant, initiator, sty and AA, after polymerization simply you can analyse AA as shell in DSC.
To my understanding you have to keep a monomer starved condition during the second polymerisation by dissolving the initiator in monomer and metering it at a rate lower than the polymerisation rate. you may have to add extra surfactant to the initially formed latex to ensure stability at concentarion level below its CMC so that polymerisation takes place only around the "core" and no shell alone polymer is formed.. Development of core shell structure is system specific and one has to develop conditions based on general principles.
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