Photoinduced reverse atom transfer radical polymerization of methyl methacrylate using camphorquinone/benzhydrol system

Abstract

A versatile initiating system composed of camphorquinone/benzhydrol and Cu II Br 2 /N,N,N ,N ,N -pentamethyldiethyl enetriamine for photoinduced reverse atom transfer radical polymerization has been developed. The control experiments, where each component is eliminated in the reaction, serve as a direct verification of the mechanism. There is poor or no control over the polymerization of methyl methacrylate in the absence of either camphorquinone or benzhydrol. The experimental molecular weights are considerably higher than theoretical values and the obtained polymers show slightly broad molecular weight distributions ranging from 1.13 to 1.51 in the process. Although at relatively lower polymerization rates, the addition of an alkyl halide to the system leads to a better control of the polymerization as reflected by the improved molecular weight distribution and chain-end functionality.

Visible light sensitive photoinitiating systems: Recent progress in cationic and radical photopolymerization reactions under soft conditions

“…Recently, many new photoinitiating systems for controlled polymerization with visible light, and even sunlight, have been reported (see Table 13) [20,21,[246][247][248][249][250][251][252][253][254][255]. These systems are mainly based on the photoinduced ATRP and/or the photoredox catalysis approach [20,21,[248][249][250][251][252][253][254][255].…”

“…These systems are mainly based on the photoinduced ATRP and/or the photoredox catalysis approach [20,21,[248][249][250][251][252][253][254][255]. The use of Cu or Ir catalysts has been found particularly appropriate, i.e., these compounds exhibit excellent visible light absorption properties.…”

Visible Light-Induced Atom Transfer Radical Polymerization for Macromolecular Syntheses

“…Although visible light induced ATRP represented well-controlled system for the polymerization of methyl acrylate, the system was less controlled toward styrene monomer due to the high quenching rate of the monomer. Quite recently a new photoinduced reverse ATRP approach using camphorquinone/benzhydrol (CQ/Bzh) as an alternative initiating system has been reported (50). In this process, triplet state CQ abstracts hydrogen from the ground state Bzh to give two ketyl type radicals, which do not react with the surrounding monomer as a result of its stability and steric hindrance.…”

Dibenzoyldiethylgermane as a visible light photo-reducing agent for CuAAC click reactions

“…This photoreducing strategy was utilized for ATRP and synthesis of macromolecular structures such as telechelic polymers, block and graft copolymers and hydrogels and organogels through CuAAC reaction. 46,[54][55][56][57][58][59][60][61][62][63][64][65][66] In another study, we applied polynuclear aromatic compounds as photosensitivers for the reduction of Cu(II) complexes to realize CuAAC reactions. 46 Table 1 comprises the previously used photoinitiators and their operative wavelength regions for CuAAC reactions.…”