RAFT Polymerization in a Miniemulsion System Using a Novel Type of Amphiphilic RAFT Agent with Poly(ethylene glycol) Bound to a Dithiobenzoate Group

Abstract

In this study, reversible addition–fragmentation chain transfer (RAFT) miniemulsion polymerization using a novel type of amphiphilic RAFT agent was investigated. The novel amphiphilic RAFT agent has a specific chemical structure in which a hydrophilic poly(ethylene glycol) chain is directly bonded to the “Z-group” position, and not the leaving group (R group), of the thiocarbonylthio group (RAFT group). As a result, the RAFT groups are localized at the interface of the water/monomer droplets (polymer particles) throughout the polymerization, unlike with a conventional amphiphilic RAFT agent. Polystyrene (PS) particles with a broad molecular weight distribution and 69% degree of livingness were successfully prepared using the novel RAFT agent in a manner similar to that for a conventional RAFT system. Notably, after the completion of polymerization, the RAFT groups could be easily removed from the dispersed PS particles via treatment with an excess of potassium persulfate, because the RAFT groups only exist near the particle surfaces.

Interfacial RAFT Miniemulsion Polymerization: Architectures from an Interface

“…Minami et al approached the interfacial polymerization from a novel perspective. A PEG chain was attached to the Z‐group rather than through the R‐group, and is the only example of a macro‐RAFT developed in this way ( 13 ) (Figure a,b).…”

“…a) Conventional macro‐RAFT agent, b) macro‐RAFT agent attached via the Z‐group, and c,d) Z‐series confocal laser scanning microscopy images of prepared polystyrene particles using the R‐ or Z‐group attached macro‐RAFT agent, respectively. Reproduced with permission . Copyright 2014, American Chemical Society.…”

Visible light‐induced RAFT polymerization of methacrylates with benzaldehyde derivatives as organophotoredox catalysts

“…Encouraged by this success, herein, we believed that it would be helpful to improve controllability by using this simple benzaldehyde photoredox catalyst in PET‐RAFT. In addition, the PET‐RAFT polymerization can be conducted in bulk, solution, dispersion, and miniemulsion . In this contribution, we presented a novel metal‐free system, in which 2,4‐dimethoxy benzaldehyde (PC1) and p ‐anisaldehyde (PC2) of different redox potentials were used as photoredox catalyst in PET‐RAFT polymerizations to afford well‐defined polymers.…”

Use of a trithiocarbonyl RAFT agent without modification as (Co)stabilizer in miniemulsion polymerization

“…Recently, in the past few years, considerable efforts have been made to perform the RAFT process in dispersed systems without the use of classic surfactants . Hawkett et al were one of the first to introduce the use of chain transfer agents (CTAs) also as stabilizers in miniemulsions .…”

“…Other research groups have also tried similar strategies to replace surfactants in RAFT miniemulsion. However, all methodologies developed to date rely on using modified polymers, block copolymers, random copolymers, or macro‐CTAs as (co)stabilizer or (co)surfactants …”