Facile iron(iii)-mediated ATRP of MMA with phosphorus-containing ligands in the absence of any additional initiators

Abstract

A series of phosphorus-containing ligands was employed to establish a novel polymerization system for the iron(III)-mediated polymerization of methyl methacrylate (MMA) just using FeCl 3 $6H 2 O or FeBr 3 as the catalyst without any additional initiators and reducing agents. The polymerization results showed that this polymerization system involving MMA/FeX 3 (X ¼ Cl, Br)/phosphorus-containing ligand was a typical "living"/controlled radical polymerization process: first-order polymerization kinetics with respect to monomer concentration and a linear increase of the molecular weight of the resultant PMMAs with conversion while keeping a narrow molecular weight distribution. Chain end analysis of the obtained PMMA based on 1 H NMR, 31 P NMR were used to confirm the precise structure of the obtained polymers.The results showed that phosphorus-containing complexes acted as both ligand and thermal radical initiators in this process, which was consistent with a reverse atom transfer radical polymerization (reverse ATRP) mechanism.

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 controlled/"living" characteristics are conrmed by a measured molecular weight value close to the theoretical one and a low PDI value. These ndings are in agreement with the results of Bai et al 58 In particular, as clearly demonstrated by Table 1, with an optimized molar ratio of 2 : 2 (entry 2) the IL may readily coordinate to FeCl 3 . With large amount of IL, with a molar ratio of 2 : 40 (entry 1), the FeCl 3 /IL complex could be preferentially destroyed, while with a FeCl 3 /IL molar ratio of 2 : 1, free FeCl 3 metal compound could potentially retard or inhibit the radical polymerization of MMA (entry 3).…”

Photoinduced Iron(III)-Mediated Atom Transfer Radical Polymerization with In Situ Generated Initiator: Mechanism and Kinetics Studies

“…Besides, an Fe­(III)-based ATRP using phosphorus ligands without any radical initiator [e.g., 2,2′-azobis­(isobutyronitrile) (AIBN)] and reducing agent was reported by Noh and co-workers, in which the authors proposed that the Fe­(III) deactivator was reduced by methyl methacrylate at 80 °C. − It should be noted that 2 equiv of phosphorus ligand was required for the catalyst coordination in these work. Nevertheless, an additional mechanism insight given by Matyjaszewski and co-wokers recently showed that phosphines play a dual role as reducing agents and ligand for Fe­(III) salt in this system. , Additionally, Noh and co-workers and Bai and co-workers reported a similar iron­(III)-based polymerization system in the absence of any additional initiators (i.e., no radical initiator or alkyl halides initiator) under high temperature. However, different underlying mechanisms were proposed by these groups.…”

“…In recent years, transition-metal complexes in a higher oxidation state or/and parts per million (ppm) catalyst loading was required in newly developed ATRP methods. , These approaches can be divided into two types by the method of continuously regenerating activators: one is a chemical method and the other is a physical method. As to the former, for example, the activators in reverse ATRP, − activators generated by electron transfer (AGET) ATRP, − activators regenerated by electron transfer (ARGET) ATRP, , initiators for continuous activator regeneration (ICAR) ATRP, − and supplemental activators and reducing agent (SARA) ATRP − were continuously regenerated through using conventional radical initiator or organic–inorganic reducing agents. Besides, an Fe­(III)-based ATRP using phosphorus ligands without any radical initiator [e.g., 2,2′-azobis­(isobutyronitrile) (AIBN)] and reducing agent was reported by Noh and co-workers, in which the authors proposed that the Fe­(III) deactivator was reduced by methyl methacrylate at 80 °C. − It should be noted that 2 equiv of phosphorus ligand was required for the catalyst coordination in these work.…”

Visible light‐driven acridone catalysis for atom transfer radical polymerization

“…Several strategies such as supplemental activator and reducing agent (SARA) ATRP (also termed single electron transfer living radical polymerization, SET‐LRP), 3 initiators for continuous activator regeneration (ICAR) ATRP, 4 activator regeneration by electron transfer (ARGET) ATRP, 5 electrochemically mediated polymerization (eATRP), 6 mechanochemically mediated polymerization (mechanoATRP) 7 and photochemically mediated procedures (photoATRP) 8 have been developed for the controlled synthesis of functional polymers. In most strategies, transition metals, such as copper, 9 iron, 10 ruthenium 11 etc., can efficiently promote the ATRP process of vinyl monomers via an activation/deactivation cycle between the predominant dormant species and a low concentration of propagating radicals, and revealed excellent control on the polymerization procedure. But left problem of metal pollutant, that only ppm level of catalyst residue in the polymer products can greatly influence their performance in electronic or biomaterial applications.…”