Beyond Traditional RAFT: Alternative Activation of Thiocarbonylthio Compounds for Controlled Polymerization

Abstract

Recent developments in polymerization reactions utilizing thiocarbonylthio compounds have highlighted the surprising versatility of these unique molecules. The increasing popularity of reversible addition–fragmentation chain transfer (RAFT) radical polymerization as a means of producing well‐defined, ‘controlled’ synthetic polymers is largely due to its simplicity of implementation and the availability of a wide range of compatible reagents. However, novel modes of thiocarbonylthio activation can expand the technique beyond the traditional system (i.e., employing a free radical initiator) pushing the applicability and use of thiocarbonylthio compounds even further than previously assumed. The primary advances seen in recent years are a revival in the direct photoactivation of thiocarbonylthio compounds, their activation via photoredox catalysis, and their use in cationic polymerizations. These synthetic approaches and their implications for the synthesis of controlled polymers represent a significant advance in polymer science, with potentially unforeseen benefits and possibilities for further developments still ahead. This Research News aims to highlight key works in this area while also clarifying the differences and similarities of each system.

Unraveling Photocatalytic Mechanism and Selectivity in PET‐RAFT Polymerization

“…This is usually done through complex photoredox and energy transfer processes and has offered a profound challenge to researchers [1][2][3] who tried to model this natural phenomenon. [4][5][6][7][8][9][10][11] As the name suggests, these photoredox catalysts harnesses the energy of visible light to accelerate a chemical reaction through electron transfer processes. Over the subsequent century, interest has grown in finding new systems that are capable of absorbing light and mediating chemical reactions for the production of fine chemicals and advanced materials.…”

Sono‐RAFT Polymerization in Aqueous Medium

“…[13] Previously,Liu et al reported on the ultrasonic irradiation of polystyrene with adithiocarbamate iniferter [14] at the chain end. Thee xtent of each is highly dependent on the irradiating frequency.Atlow frequencies ( % 20 kHz) physical forces are dominant with minimal chemical effects,w hile at higher frequencies (> 200 kHz) the situation is reversed (Scheme 1).…”

Nahinfrarot‐sensibilisierte photoinduzierte ATRP mit einer Kupfer(II)‐Katalysatorkonzentration im ppm‐Bereich

“…[17] Erst kürzlich wurde die NIR-initiierte RAFT-Polymerisation unter Verwendung von aufwärtskonvertierenden Nanopartikeln erfolgreich angewendet, um ein funktionelles Nanohybrid aus einem anorganischen Kern und einer Polymerschale zur Anwendung in der Krebs-Theranostik [18] aufzubauen. [17] Erst kürzlich wurde die NIR-initiierte RAFT-Polymerisation unter Verwendung von aufwärtskonvertierenden Nanopartikeln erfolgreich angewendet, um ein funktionelles Nanohybrid aus einem anorganischen Kern und einer Polymerschale zur Anwendung in der Krebs-Theranostik [18] aufzubauen.…”