Facile “Living” Radical Polymerization of Methyl Methacrylate in the Presence of Iniferter Agents: Homogeneous and Highly Efficient Catalysis from Copper(II) Acetate

Plasmonic-redox controlled atom transfer radical polymerization

Plasmonic-ATRP has been developed in which Cu(i) species are (re)generated via photo-redox reactions both directly by hot electrons and indirectly by hot holes, in which the polymerization degree and molecular weight can be regulated by controlling the rate of plasmonic hot carrier extraction.

Redox-Initiated Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization

Reversible addition–fragmentation chain transfer (RAFT) polymerization initiated by a radical-forming redox reaction between a reducing and an oxidizing agent (i.e. ‘redox RAFT’) represents a simple, versatile, and highly useful platform for controlled polymer synthesis. Herein, the potency of a wide range of redox initiation systems including enzyme-mediated redox reactions, the Fenton reaction, peroxide-based reactions, and metal-catalyzed redox reactions, and their application in initiating RAFT polymerization, are reviewed. These redox-RAFT polymerization methods have been widely studied for synthesizing a broad range of homo- and co-polymers with tailored molecular weights, compositions, and (macro)molecular structures. It has been demonstrated that redox-RAFT polymerization holds particular promise due to its excellent performance under mild conditions, typically operating at room temperature. Redox-RAFT polymerization is therefore an important and core part of the RAFT methodology handbook and may be of particular importance going forward for the fabrication of polymeric biomaterials under biologically relevant conditions or in biological systems, in which naturally occurring redox reactions are prevalent.

Photochemistry for Well-Defined Polymers in Aqueous Media: From Fundamentals to Polymer Nanoparticles to Bioconjugates

This review article highlights recent developments in the field of photochemistry and photochemical reversible deactivation radical polymerization applied to aqueous polymerizations. Photochemistry is a topic of significant interest in the fields of organic, polymer, and materials chemistry because it allows challenging reactions to be performed under mild conditions. Aqueous polymerization is of significant interest because water is an environmentally benign solvent, and the use of water enables complex polymer self-assembly and bioconjugation processes to occur. This review focuses on powerful new developments in photochemical aqueous polymerization reactions and their applications to the synthesis of well-defined polymer nano-objects and bioconjugates. It is anticipated that these aqueous photopolymerizations will enable the next generation of self-assembled structures and biohybrid materials to be developed under mild and environmentally friendly conditions.

Photocatalysis in organic and polymer synthesis

This review, with over 600 references, summarizes the recent applications of photoredox catalysis for organic transformation and polymer synthesis. Photoredox catalysts are metallo- or organo-compounds capable of absorbing visible light, resulting in an excited state species. This excited state species can donate or accept an electron from other substrates to mediate redox reactions at ambient temperature with high atom efficiency. These catalysts have been successfully implemented for the discovery of novel organic reactions and synthesis of added-value chemicals with an excellent control of selectivity and stereo-regularity. More recently, such catalysts have been implemented by polymer chemists to post-modify polymers in high yields, as well as to effectively catalyze reversible deactivation radical polymerizations and living polymerizations. These catalysts create new approaches for advanced organic transformation and polymer synthesis. The objective of this review is to give an overview of this emerging field to organic and polymer chemists as well as materials scientists.

Photocatalyzed iron-based ATRP of methyl methacrylate using 1,3-dimethyl-2-imidazolidinone as both solvent and ligand

A simple photocatalyzed Fe-based ATRP of MMA was conducted under UV irradiation using the “green” solvent DMI as both the solvent and ligand.

A facile, simple, and inexpensive ionic liquid, 1-alkyl-3-methylimidazole chloride, as ligand for the iron(iii)-mediated reverse atom transfer radical polymerization of methyl methacrylate

The facile, simple, and inexpensive ILs, 1-alkyl-3-methylimidazole chloride ([Rmim][Cl]), are explored for the first time as ligands for the reverse ATRP of methacrylates.

Facile synthesis of poly(vinyl acetate)-b-polystyrene copolymers mediated by an iniferter agent using a single methodology

A novel and convenient method to synthesize diblock copolymers containing both conjugated and non-conjugated monomers, PVAc-b-PS, was established by using a single iniferter methodology.

Visible-light-induced living radical polymerization using in situ bromine-iodine transformation as an internal boost

A new visible-light-induced methodology, termed as “bromine-iodine transformation activated living radical polymerization”, was successfully established to build a “bridge” between ATRP and iodine-mediated LRP techniques.

Visible light-induced PET-RAFT polymerization of methacrylates with novel organic photocatalysts

PET-RAFT polymerization was successfully carried out under irradiation of various LED lights at room temperature by using two novel organic agents 4-methoxybenzaldehyde and 2,4,6-tri-(p-methoxyphenyl) pyrylium tetrafluoroborate for the first time.

Mechanosynthesized copper(i) complex based initiating systems for redox polymerization: towards upgraded oxidizing and reducing agents

Significant improvements of the recently proposed Cu(i)/VitC + water/dibenzoyl peroxide (BPO) system for the redox free radical polymerization of methacrylates in air are presented here.

Metal-Free Atom Transfer Radical Polymerization of Methyl Methacrylate with ppm Level of Organic Photocatalyst

It is well known that the recently developed photoinduced metal-free atom transfer radical polymerization (ATRP) has been considered as a promising methodology to completely eliminate transition metal residue in polymers. However, a serious problem needs to be improved, namely, large amount of organic photocatalysts should be used to keep the controllability over molecular weights and molecular weight distributions. In this work, a novel photocatalyst 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) with strong excited state reduction potential is successfully used to mediate a metal-free ATRP of methyl methacrylate just with parts per million (ppm) level usage under irradiation of blue light emitting diode at room temperature, using ethyl α-bromophenyl-acetate as a typical initiator with high initiator efficiency. The polymerization kinetic study, multiple controlled "on-off" light switching cycle regulation, and chain extension experiment confirm the "living"/controlled features of this promising photoinduced metal-free ATRP system with good molecular weight control in the presence of ppm level photocatalyst 4CzIPN.

Electrochemically mediated atom transfer radical polymerization of n-butyl acrylate on non-platinum cathodes

Inexpensive metals and metal alloys were used as cathodes in well-controlled, electrochemically mediated ATRP ofn-butyl acrylate in DMF with the ppm level of catalysts.

Metal-free photoinduced electron transfer–atom transfer radical polymerization (PET–ATRP) via a visible light organic photocatalyst

This work developed the first example of PET-ATRP using a reductive pathway, which provides new opportunities for the synthesis of well-controlled polymer architectures through a photochemical approach.

Synthesis of amphiphilic nanoparticles and multi-block hydrophilic copolymers by a facile and effective “living” radical polymerization in water

A convenient and robust approach using MANDC-COOH as the initiator and oxidatively stable Cu(OAc)₂as the catalyst to synthesize amphiphilic nanoparticles and hydrophilic multi-block copolymers was successfully developed in water.

Recent Progress on Transition Metal Catalyst Separation and Recycling in ATRP

Atom transfer radical polymerization (ATRP) is a versatile and robust tool to synthesize a wide spectrum of monomers with various designable structures. However, it usually needs large amounts of transition metal as the catalyst to mediate the equilibrium between the dormant and propagating species. Unfortunately, the catalyst residue may contaminate or color the resultant polymers, which limits its application, especially in biomedical and electronic materials. How to efficiently and economically remove or reduce the catalyst residue from its products is a challenging and encouraging task. Herein, recent advances in catalyst separation and recycling are highlighted with a focus on (1) highly active ppm level transition metal or metal free catalyzed ATRP; (2) post-purification method; (3) various soluble, insoluble, immobilized/soluble, and reversible supported catalyst systems; and (4) liquid-liquid biphasic catalyzed systems, especially thermo-regulated catalysis systems.

A well-defined, versatile photoinitiator (salen)Co-CO2CH3 for visible light-initiated living/controlled radical polymerization

The control of the polymerization of a wide range of monomers under mild conditions by a single catalyst remains a major challenge in polymer science. We report a versatile, well-defined organocobalt salen complex to control living radical polymerization of different categories of monomers, including acrylates, acrylamides and vinyl acetate, under visible light irradiation at ambient temperature. Both household light and sunlight were effectively applied in the synthesis of polymers with controlled molecular weights and narrow polydispersities. Narrowly dispersed block copolymers (Mw/Mn < 1.2) were obtained under various conditions. The structures of the polymers were analyzed by 1H NMR, 2D NMR, 13C NMR, GPC, MALDI-TOF-MS and isotopic labeling experiments, which showed that the ω and α ends of the polymer chains were capped with (salen)Co and -CO2CH3 segments, respectively, from the photoinitiator (salen)Co-CO2CH3. The ω end was easily functionalized through oxygen insertion followed by hydrolysis from 18O2 to -18OH. This robust system can proceed without any additives, and offers a versatile and green way to produce well-defined homo and block copolymers.

Iron-catalyzed atom transfer radical polymerization

This article reviews the preparation of polymers using iron-catalyzed atom transfer radical polymerization.

Amide group-containing polar solvents as ligands for iron-catalyzed atom transfer radical polymerization of methyl methacrylate

Iron-catalyzed ATRP of MMA using polar solvents based on amide groups as ligands is reported.

Synthesis of non-fouling poly[N-(2-hydroxypropyl)methacrylamide] brushes by photoinduced SET-LRP

Surface-initiated photoinduced SET-LRP of N-(2-hydroxypropyl)methacrylamide from an initiator-containing monolayer yields micropatterned brushes resistant to blood plasma fouling.

Facile and universal photo-induced living radical polymerization system mediated by iniferter agent and copper(ii) acetate at ambient temperature

A facile and universal photo-induced living radical polymerization with a wide range of monomers was developed in the presence of iniferter agent MANDC and organic catalyst copper(ii) acetate under UV irradiation at ambient temperature.