This paper provides a third update to the review of reversible deactivation radical polymerization (RDRP) achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition-fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669) and the second in December 2009 (Aust. J. Chem. 2009, 62, 1402). This review cites over 700 publications that appeared during the period mid 2009 to early 2012 covering various aspects of RAFT polymerization which include reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses, and a diverse range of applications. This period has witnessed further significant developments, particularly in the areas of novel RAFT agents, techniques for end-group transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.

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Living Radical Polymerization by the RAFT Process - A Second Update

The development of microgels/nanogels for drug delivery applications

Radical addition-fragmentation chemistry in polymer synthesis

Herein we describe a versatile new strategy for producing monodisperse solid particles with sizes from 20 to 1000 mm. The method involves the formation of monodisperse liquid droplets by using a microfluidic device and shaping the droplets in a microchannel and then solidifying these drops in situ either by polymerizing a liquid monomer or by lowering the temperature of a liquid that sets thermally. This method has the following features: 1) It produces particles with an exceptionally narrow range of sizes. 2) A new level of control over the shapes of the particles is offered. 3) The mechanism for droplet formation allows the use of a wide variety of materials including gels, metals, polymers, and polymers doped with functional additives. 4) The procedure can be scaled up to produce large numbers of particles. A number of methods exist for making inorganic and organic particles with narrow polydispersity. Inorganic colloids are typically prepared by precipitation reactions from organometallic precursors. Polymer colloids with sizes from 20 nm to approximately 1 mm are usually prepared by a variation of emulsion polymerization techniques. Larger beads are accessible through miniemulsion polymerization,

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/ange.200590085

Generation of Monodisperse Particles by Using Microfluidics: Control over Size, Shape, and Composition

Electrochemical reduction of an exemplary ATRP catalyst, C 11 Br 2 /Me 6 TREN, is shown to be an efficient process to mediate and execute an ATRP. The onset of polymerization occurs only through passage of a cathodic current achieved under a reductive potential to form Cu 1 Br 2 /Me 6 TREN, within the reaction medium. Unprecedented control over the polymerization kinetics can be attained through electrochemical methods by modulating the magnitude of the applied potential allowing polymerization rate enhancement or retardation. Additional polymerization control is gained through electrochemical “dials” allowing polymerization rate enhancements achieved by larger applied potentials and the ability to successfully switch a polymerization “on” and “off between dormant and active states by application of multistep intermittent potentials.

https://science.sciencemag.org/content/sci/332/6025/81.full.pdf

Electrochemically mediated atom transfer radical polymerization

We describe a two-stage dispersion polymerization process to prepare monodisperse micrometer-sized polymer particles in which problematic reagents, such as functional monomers and cross-linkers that commonly disrupt the particle-forming process, were added to the reaction after the nucleation stage was complete. Comonomers added after this point became incorporated into the particles without disturbing the final particle size and size distribution. In this way dye-labeled or functional group-containing micrometer-sized particles with a very narrow size distribution were prepared. By varying the amount of monomer added in the second stage, the final particle diameter could be controlled precisely. Most important of all, this synthetic strategy allowed us to prepare cross-linked particles containing up to 3 mol % cross-linking agent.

Two-Stage Dispersion Polymerization toward Monodisperse, Controlled Micrometer-Sized Copolymer Particles

It is well-known that cross-linking agents such as divinylbenzene (DVB) interfere with the dispersion polymerization of styrene in ethanol, a reaction carried out in the presence of polymeric stabilizers such as poly(vinylpyrrolidone). Small amounts of DVB broaden the particle size distribution and lead to irregular particles, whereas modest amounts lead to coagulation. We report that many of these problems can be avoided if one delays the addition of the cross-linking agent until after the end of the nucleation stage of the reaction (e.g., at less than 5% monomer conversion). In this way one can obtain monodisperse polystyrene particles containing 1 wt % ethylene glycol dimethacrylate (EGDMA) as a cross-linker. A second set of problems arises if the cross-linking agent is consumed too early in the reaction, presumably because early network formation limits the swellability of the growing particles. These problems can be overcome by feeding DVB into the reaction over 12 h or by adding EGDMA in successive ...

Cross-Linked, Monodisperse, Micron-Sized Polystyrene Particles by Two-Stage Dispersion Polymerization

Living/controlled radical dispersion polymerization of styrene was carried out in ethanol and in ethanol−water mixtures in the presence of perfluorohexyl iodide (C6F13I, 2−5 wt % based on styrene) as a degenerative chain transfer (DCT) agent or 1-cyano-1-methylpropyl dithiobenzoate (CMPDB, 0.5 and 1.0 mol % based on styrene) as a reversible addition−fragmentation chain transfer (RAFT) agent. These reagents disrupt the nucleation stage of particle formation when present at the start of the reaction. If their addition is delayed until the nucleation stage is complete, the reaction acquires the characteristics of a living/controlled radical polymerization:  Mn increases linearly with the monomer conversion, and the molar mass distribution is much narrower (minimal Mw/Mn:  1.2) than polystyrene prepared without C6F13I or CMPDB. For reactions in ethanol, at low molar mass, the particles formed have a broad size distribution as a consequence of the solubility of the polymer at the reaction temperature, followed...

Monodisperse, Micron-Sized Reactive Low Molar Mass Polymer Microspheres by Two-Stage Living Radical Dispersion Polymerization of Styrene

Monodisperse carboxylated micrometer-sized polystyrene particles were synthesized by dispersion polymerization of styrene in ethanol and in 95% ethanol−water in the presence of acrylic acid (AA) as...

Jing-She Song

Papers

Two-Stage Dispersion Polymerization toward Monodisperse, Controlled Micrometer-Sized Copolymer Particles

Cross-Linked, Monodisperse, Micron-Sized Polystyrene Particles by Two-Stage Dispersion Polymerization

Monodisperse, Micron-Sized Reactive Low Molar Mass Polymer Microspheres by Two-Stage Living Radical Dispersion Polymerization of Styrene

Monodisperse Micrometer-Size Carboxyl-Functionalized Polystyrene Particles Obtained by Two-Stage Dispersion Polymerization

Monodisperse, controlled micron-size dye-labeled polystyrene particles by two-stage dispersion polymerization