A Simple and Green Oxygen‐Tolerant RAFT Polymerization without Additional Catalyst and Initiator

Abstract

Oxygen‐tolerant reversible addition‐fragmentation chain transfer polymerization (RAFT) can be successfully achieved through the addition of organic and inorganic photoredox catalysts or other additives. Thus, developing a simple oxygen‐tolerant RAFT without additional catalyst and initiator will augment the development of this field. In this work, two‐component systems, 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and 4‐cyanopentanoic acid dithiobenzoate (CPADB), have been successfully applied to develop green and oxygen‐tolerant RAFT under aqueous conditions without any additional catalysts, where dithioester CPADB was employed as an iniferter agent (initiator‐transfer‐terminator) for polymerization control, as well as an intrinsic photoredox catalyst for deoxygenation. DMAEMA was utilized as monomer and electron donor. In the present work, dithioester‐assisted oxygen removal in aqueous RAFT photopolymerization is reported for the first time. This work provides a simple and green method for oxygen‐tolerant RAFT polymerization.

Photocontrolled RAFT polymerization: past, present, and future

“…Very recently, Zhang, Weng, and coworkers reported an oxygentolerant polymerization system using CPADB under irradiation with a household lamp (14 W, 2.4 mW cm À2 ) where the amine was incorporated as a part of 2-(dimethylamino)-, 2-(diethylamino)-, or 1-(dipropylamino)ethyl methacrylate monomers. 153 However, with a target degree of polymerization (DP) of 400, the relatively high dispersity (1.42-2.12), deviation of molecular weight from theoretical values, and/or the color change of solution from red to yellow (i.e., degradation of CPADB) suggested the need for further optimization of reaction conditions. Gibson and coworkers disregarded the high dispersities of…”

3D Printing/Vat Photopolymerization of Photopolymers Activated by Novel Organic Dyes as Photoinitiators

“…In terms of the results, the photoinduced RAFT polymerization of the mixture in the ratio of [DMAEMA] 0 :[CPADB] 0 = 400:1 during a flame-sealing process without prior deoxygenation successfully proceeded in a controlled fashion, and it produced a high conversion rate of 75% after 24 h. Remarkably, the monomer conversions also increased with the molecular weight and viscosity, proving the fact that dithioester can be used as an iniferter agent to conduct RAFT polymerization under light irradiation. Interestingly, the polymerization in this work was carried out under a simple light source from a household lamp (14 W, 2.4 mW/cm 2 ) [75]. As a non-toxic, cheap, and environmentally friendly solvent, water also can be utilized for photopolymerizations to replace the organic solvents that are used in the traditional method.…”

“…[]*: excited state of photoredox catalyst. Adapted from Reference [75] with permission from the European Chemical Societies.…”