Controlled radical polymerization of styrene by iodine transfer polymerization (ITP) in ab initio emulsion polymerization

•Ab initio iodine transfer emulsion polymerization of styrene is performed.•Colloidally stable and uncoloured monomodal living latex particles are obtained.•Methyl-2-iodopropionate is used as reversible chain transfer agent.•A better control of Mn is obtained at 68 °C (VA-057) rather than at 80 °C (V-501).•Block copolymerization with butyl acrylate is accomplished from a living seed latex.

The use of iodocompounds in radical polymerization presents a straightforward way to prepare controlled macromolecular architectures. Herein, ab initio emulsion polymerization of styrene has been successfully performed by iodine transfer polymerization using methyl-2-iodopropionate as transfer agent, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057) as initiator and dodecyl sulfate sodium salt (SDS) as surfactant, yielding stable and uncoloured latexes (e.g. styrene conversion = 76%, Mn,theoretical = 7800 g mol−1, Mn,SEC = 8400 g mol−1, Mw/Mn = 1.84, particle diameter dp = 55 nm with a monomodal particle size distribution). Hence, the molecular weight of the polymer chains could be accurately controlled by the concentration of transfer agent. Furthermore, a poly(styrene)-b-poly(styrene-co-butyl acrylate) block copolymer latex was synthesized in seeded emulsion polymerization, proving the living character of the polymerization.

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