Successful Miniemulsion ATRP Using an Anionic Surfactant: Minimization of Deactivator Loss by Addition of a Halide Salt

Abstract

To date, it has been generally assumed, based on early experimental work, that ATRP in aqueous dispersed systems is incompatible with anionic surfactants. In the present work, it is clarified that this incompatibility originates in the anionic surfactant (sodium dodecyl sulfate, SDS) displacing the halide ligand from the Cu II bromide-based deactivator, converting it to a Cu II complex, unable to deactivate radicals. This results in a very high polymerization rate as well as essentially no control over the molecular weight distribution. It is demonstrated how such loss of deactivator can be minimized by the addition of a source of halide ions, thus enabling one to conduct ATRP in aqueous dispersed systems using commonly available and inexpensive anionic surfactants such as SDS.

Miniemulsion ARGET ATRP via Interfacial and Ion-Pair Catalysis: From ppm to ppb of Residual Copper

“…NaBr (0.1 M) was added to increase the stability of the Br–Cu II L + deactivator, which could otherwise dissociate to Cu II L 2+ + Br − in aqueous media. 52,53 The appropriate amount of AsAc was injected dropwise during the first 3 min of the reaction, considering that reduction of all Cu II requires [AsAc]/[Cu II ] = 0.5. 46 …”

Synthesis and Applications of Protein/Peptide-Polymer Conjugates

“…Under standard aqueous SET‐LRP conditions, polymerization of NIPAM and OEGA from these dispersed macroinitiators was not well controlled ( Đ > 1.99). Poor control over polymerization had previously been reported during ATRP in emulsion using anionic surfactants which were implicated in the loss of halide ions from the solutions . This causes an unfavourable imbalance in the activation‐deactivation equilibrium which can be countered by the addition of NaBr to the surfactant solution.…”

“…Poor control over polymerization had previously been reported during ATRP in emulsion using anionic surfactants which were implicated in the loss of halide ions from the solutions. [95] This causes an unfavourable imbalance in the activation-deactivation equilibrium which can be countered by the addition of NaBr to the surfactant solution. In the presence of an excess of NaBr, control over the polymerization of NIPAM was shown to be much improved from both lysozyme and sCT macroinitiators (-D < 1.25).…”

Mechanistic Aspects of Aqueous Heterogeneous Radical Polymerization of Styrene under Compressed CO2

“…Miniemulsion polymerization, in which case the dispersed phase comprises typically vinyl monomer, has received significant attention because polymer particles are generated directly from monomer droplets . This circumvents the requirement for diffusion across the aqueous phase to particles (as is the case in a conventional emulsion polymerization), thus opening up a range of possibilities in terms of nanoparticle synthesis, e.g., implementation of controlled/living radical polymerization (CLRP), as well as synthesis of organic/inorganic hybrid nanoparticles and nanocapsules (hollow nanoparticles) …”