Ab initio RAFT emulsion polymerization mediated by small cationic RAFT agents to form polymers with low molar mass dispersity

Stace, Sarah J; Vanderspikken, Jochen; Howard, Shaun C; Li, Guoxin; Muir, Benjamin W; Fellows, Christopher M; Keddie, Daniel J; Moad, Graeme

doi:10.1039/C9PY00893D

Author(s)

Stace, Sarah J

Vanderspikken, Jochen

Howard, Shaun C

Li, Guoxin

Muir, Benjamin W

Fellows, Christopher M

Keddie, Daniel J

Moad, Graeme

Publication Date

2019-10-07

Abstract

We report on low molar mass cationic RAFT agents that provide predictable molar mass and low molar mass dispersities (Đm) in ab initio emulsion polymerization. Thus RAFT emulsion polymerization of styrene in the presence of the protonated RAFT agent, ((((cyanomethyl)thio)carbonothioyl)(methyl)amino)pyridin-1-ium toluenesulfonate (4), and the analogous methyl-quaternized RAFT agents, 4-((((cyanomethyl)thio)carbonothioyl)(methyl)amino)-1-methylpyridin-1-ium dodecyl sulfate (6), provide low dispersity polystyrene with Đm 1.2–1.4 for Mn ∼ 20 000. We postulate that the success of ab initio emulsion polymerization with 4 is due to the hydrophilicity of the pyridinium group, which is such that the water soluble RAFT agent partitions predominantly into the aqueous phase under the conditions of the experiment and that 4 provides little retardation. With 6, when the counterion is dodecyl sulfate, we can achieve "surfactant-free" RAFT emulsion polymerization to provide a low Đm polystyrene. However, the RAFT end-group is lost on isolation of the polymer. Preliminary results show that this class of RAFT agent is broadly applicable in ab initio emulsion polymerization of other more-activated monomers (e.g., butyl acrylate, butyl methacrylate). Furthermore, cyanomethyl(pyridin-4-yl)carbamodithioate (3, the RAFT agent in neutral form) provides molar mass control and Đm < 1.8 in ab initio emulsion polymerization of less activated monomers, specifically, the vinyl esters, vinyl acetate and vinyl benzoate.

Citation

Polymer Chemistry, 10(37), p. 5044-5051

ISSN

1759-9962

1759-9954

Link

https://hdl.handle.net/1959.11/29350

Language

en

Publisher

Royal Society of Chemistry

Title

Ab initio RAFT emulsion polymerization mediated by small cationic RAFT agents to form polymers with low molar mass dispersity

Type of document

Journal Article

Entity Type

Publication

Author(s)	Stace, Sarah J Vanderspikken, Jochen Howard, Shaun C Li, Guoxin Muir, Benjamin W Fellows, Christopher M Keddie, Daniel J Moad, Graeme
Publication Date	2019-10-07
Abstract	<p>We report on low molar mass cationic RAFT agents that provide predictable molar mass and low molar mass dispersities (<i>Đ</i><sub>m</sub>) in <i>ab initio</i> emulsion polymerization. Thus RAFT emulsion polymerization of styrene in the presence of the protonated RAFT agent, ((((cyanomethyl)thio)carbonothioyl)(methyl)amino)pyridin-1-ium toluenesulfonate (<b>4</b>), and the analogous methyl-quaternized RAFT agents, 4-((((cyanomethyl)thio)carbonothioyl)(methyl)amino)-1-methylpyridin-1-ium dodecyl sulfate (<b>6</b>), provide low dispersity polystyrene with <i>Đ</i><sub>m</sub> 1.2–1.4 for <i>M</i><sub>n</sub> ∼ 20 000. We postulate that the success of <i>ab initio</i> emulsion polymerization with <b>4</b> is due to the hydrophilicity of the pyridinium group, which is such that the water soluble RAFT agent partitions predominantly into the aqueous phase under the conditions of the experiment and that <b>4</b> provides little retardation. With <b>6</b>, when the counterion is dodecyl sulfate, we can achieve "surfactant-free" RAFT emulsion polymerization to provide a low <i>Đ</i><sub>m</sub> polystyrene. However, the RAFT end-group is lost on isolation of the polymer. Preliminary results show that this class of RAFT agent is broadly applicable in <i>ab initio</i> emulsion polymerization of other more-activated monomers (<i>e.g.</i>, butyl acrylate, butyl methacrylate). Furthermore, cyanomethyl(pyridin-4-yl)carbamodithioate (<b>3</b>, the RAFT agent in neutral form) provides molar mass control and <i>Đ</i><sub>m</sub> < 1.8 in <i>ab initio</i> emulsion polymerization of less activated monomers, specifically, the vinyl esters, vinyl acetate and vinyl benzoate.</p>
Citation	Polymer Chemistry, 10(37), p. 5044-5051
ISSN	1759-9962 1759-9954
Link	https://hdl.handle.net/1959.11/29350
Language	en
Publisher	Royal Society of Chemistry
Title	Ab initio RAFT emulsion polymerization mediated by small cationic RAFT agents to form polymers with low molar mass dispersity
Type of document	Journal Article
Entity Type	Publication

Ab initio RAFT emulsion polymerization mediated by small cationic RAFT agents to form polymers with low molar mass dispersity

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