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Abstract Traditional mechanochemically controlled reversible‐deactivation radical polymerization (RDRP) utilizes ultrasound or ball milling to regenerate activators, which induce side reactions because of the high‐energy and high‐frequency stimuli. Here, we propose a facile approach for tribochemically controlled atom transfer radical polymerization (tribo‐ATRP) that relies on contact‐electro‐catalysis (CEC) between titanium oxide (TiO₂) particles and CuBr₂/tris(2‐pyridylmethylamine (TPMA), without any high‐energy input. Under the friction induced by stirring, the TiO₂particles are electrified, continuously reducing CuBr₂/TPMA into CuBr/TPMA, thereby conversing alkyl halides into active radicals to start ATRP. In addition, the effect of friction on the reaction was elucidated by theoretical simulation. The results indicated that increasing the frequency could reduce the energy barrier for the electron transfer from TiO₂particles to CuBr₂/TPMA. In this study, the design of tribo‐ATRP was successfully achieved, enabling CEC (ca. 10 Hz) access to a variety of polymers with predetermined molecular weights, low dispersity, and high chain‐end fidelity. 

Abstract Carbon nanomaterials, specifically carbon dots and carbon nitrides, play a crucial role as heterogeneous photoinitiators in both radical and cationic polymerization processes. These recently introduced materials offer promising solutions to the limitations of current homogeneous systems, presenting a novel approach to photopolymerization. This review highlights the preparation and photocatalytic performance of these nanomaterials, emphasizing their application in various polymerization techniques, including photoinduced i) free radical, ii) RAFT, iii) ATRP, and iv) cationic photopolymerization. Additionally, it discusses their potential in addressing contemporary challenges and explores prospects in this field. Moreover, carbon nitrides, in particular, exhibit exceptional oxygen tolerance, underscoring their significance in radical polymerization processes and allowing their applications such as 3D printing, surface modification of coatings, and hydrogel engineering. 

Abstract Atom transfer radical polymerization (ATRP) of oligo(ethylene oxide) monomethyl ether methacrylate (OEOMA₅₀₀) in water is enabled using CuBr₂with tris(2‐pyridylmethyl)amine (TPMA) as a ligand under blue or green‐light irradiation without requiring any additional reagent, such as a photo‐reductant, or the need for prior deoxygenation. Polymers with low dispersity (Đ = 1.18–1.25) are synthesized at high conversion (>95%) using TPMA from three different suppliers, while no polymerization occurred with TPMA is synthesized and purified in the laboratory. Based on spectroscopic studies, it is proposed that TPMA impurities (i.e., imine and nitrone dipyridine), which absorb blue and green light, can act as photosensitive co‐catalyst(s) in a light region where neither pure TPMA nor [(TPMA)CuBr]⁺absorbs light. 

Abstract Photoinduced initiators for continuous activator regeneration atom transfer radical polymerization (PICAR ATRP) using sodium pyruvate and blue light (λ_max = 456 nm) is reported. Water‐soluble oligo(ethylene oxide) methyl ether methacrylate (OEOMA₅₀₀) was polymerized under biologically relevant conditions. Polymerizations were conducted with 1000 ppm (with respect to the monomer) concentrations of CuBr₂, tris(2‐pyridylmethyl)amine, and 1000 ppm or less FeCl₃as a cocatalyst in water. Well‐defined polymers with up to 90% monomer conversion, high molecular weights (M_n > 190,000), and low dispersity (1.14 < Ð < 1.19) were synthesized in less than 60 min. The polymerization rate and dispersity were tuned by varying the concentration of sodium pyruvate (SP), iron, and supporting halide, as well as light intensity. The Cu/Fe dual catalysis provided oxygen tolerance enabling rapid, well‐controlled, aqueous PICAR ATRP of OEOMA₅₀₀without deoxygenation. 

Abstract Atom transfer radical polymerization (ATRP) is one of the most powerful methods to prepare well‐defined (co)polymers. Cu‐catalyzed ATRP methods are most commonly used because of the excellent control and tunable catalytic activities via ligand functionalization. This minireview summarizes the development of Cu‐catalyzed ATRP in the presence of cocatalysts, which are used to regenerate Cu^Icomplex activators during polymerizations. Fundamentals of Cu‐based ATRP catalysts are first introduced, followed by the discussion of different types of cocatalysts in different Cu‐catalyzed ATRP methods. Recent developments of photochemical cocatalysts for oxygen‐tolerant ATRP and ATRP using long‐wavelength irradiation are highlighted, which significantly expand the applications of Cu‐catalyzed ATRP. Methods to study the properties of cocatalysts and their roles in Cu‐catalyzed ATRP are discussed, with an outlook for the future development of cocatalysts. 

Abstract Simple synthetic routes to regioselectively deuterated tris[2‐(dimethylamino)ethyl]amine (Me₆TREN) variants are described. Imine formation with formaldehyde‐d₂from tris(2‐aminoethyl)amine (TREN) and subsequent reductions with NaBD₄afforded N[CH₂CH₂N(CD₃)₂]₃ord₁₈‐Me₆TREN in 79 % yield. A trisubstitution protocol from 2‐bromo‐N,N‐dimethylacetamide and ammonium carbonate and subsequent reduction of the N(CH₂CONMe₂)₃intermediate by lithium aluminum deuteride has afforded N[CH₂CD₂N(CH₃)₂]₃or (d₆‐arm)‐Me₆TREN in three steps and 52 % overall yield. A similar protocol from 2‐bromo‐N,N‐dimethyl‐d₂‐acetamide, obtained in two steps fromd₄‐acetic acid, with reduction of the N(CD₂CONMe₂)₃intermediate by lithium aluminum hydride has afforded N[CD₂CH₂N(CH₃)₂]₃or (d₆‐cap)‐Me₆TREN in four steps and 13 % overall yield from CD₃COOD. 

Abstract Reversible‐deactivation radical polymerizations (RDRPs) have revolutionized synthetic polymer chemistry. Nowadays, RDRPs facilitate design and preparation of materials with controlled architecture, composition, and functionality. Atom transfer radical polymerization (ATRP) has evolved beyond traditional polymer field, enabling synthesis of organic–inorganic hybrids, bioconjugates, advanced polymers for electronics, energy, and environmentally relevant polymeric materials for broad applications in various fields. This review focuses on the relation between ATRP technology and the 12 principles of green chemistry, which are paramount guidelines in sustainable research and implementation. The green features of ATRP are presented, discussing the environmental and/or health issues and the challenges that remain to be overcome. Key discoveries and recent developments in green ATRP are highlighted, while providing a perspective for future opportunities in this area. 

Abstract Halogen exchange in atom transfer radical polymerization (ATRP) is an efficient way to chain‐extend from a less active macroinitiator (MI) to a more active monomer. This has been previously achieved by using CuCl/L in the equimolar amount to P_n−Br MI in the chain extension step. However, this approach cannot be effectively applied in systems based on regeneration of activators (ARGET ATRP), since they operate with ppm amounts of catalysts. Herein, a catalytic halogen exchange procedure is reported using a catalytic amount of Cu in miniemulsion ARGET ATRP to chain‐extend from a less active poly(n‐butyl acrylate) (PBA) MI to a more active methyl methacrylate (MMA) monomer. Influence of different reagents on the initiation efficiency and dispersity is studied. Addition of 0.1mNaCl or tetraethylammonium chloride to ATRP of MMA initiated by methyl 2‐bromopropionate leads to high initiation efficiency and polymers with low dispersity. The optimized conditions are then employed in chain extension of PBA MI with MMA to prepare diblock and triblock copolymers. 

Abstract A facile and efficient two‐step synthesis ofp‐substituted tris(2‐pyridylmethyl)amine (TPMA) ligands to form Cu complexes with the highest activity to date in atom transfer radical polymerization (ATRP) is presented. In the divergent synthesis,p‐Cl substituents in tris(4‐chloro‐2‐pyridylmethyl)amine (TPMA^3Cl) were replaced in one step and high yield by electron‐donating cyclic amines (pyrrolidine (TPMA^PYR), piperidine (TPMA^PIP), and morpholine (TPMA^MOR)) by nucleophilic aromatic substitution. The [Cu^II(TPMA^NR2)Br]⁺complexes exhibited larger energy gaps between frontier molecular orbitals and >0.2 V more negative reduction potentials than [Cu^II(TPMA)Br]⁺, indicating >3 orders of magnitude higher ATRP activity. [Cu^I(TPMA^PYR)]⁺exhibited the highest reported activity for Br‐capped acrylate chain ends in DMF, and moderate activity toward C−F bonds at room temperature. ATRP ofn‐butyl acrylate using only 10–25 part per million loadings of [Cu^II(TPMA^NR2)Br]⁺exhibited excellent control.