Living Covalent-Anionic-Radical Polymerization via a Barbier Strategy

Abstract

The developments of the living alkene polymerization method have achieved great progress and enabled the precise synthesis of important polyalkenes with controlled molecular weight, molecular weight distribution, and architecture through an anionic, cationic or radical strategy. However, it is still challenging to develop a living alkene polymerization method through an all-in-one strategy where anionic and radical characteristics are merged into one polymerization species. Here, a versatile living polymerization method is reported by introducing a well-established all-in-one covalent-anionic-radical Barbier strategy into a living polymerization. Through this living covalent-anionic-radical Barbier polymerization (Barbier CARP), narrow distributed polystyrenes, with Đ as low as 1.05, are successfully prepared under mild conditions with a full monomer conversion by using wide varieties of organohalides, for example, alkyl, benzyl, allyl, and phenyl halides, as initiators with Mg in one pot. This living covalent-anionic-radical polymerization via a Barbier strategy expands the methodology library of polymer chemistry and enables living polymerization with an unconventional polymerization mode.

Turbo-Grignard Reagent Mediated Polymerization of Styrene under Mild Conditions Capable of Low Đ and Reactive Hydrogen Compatibility

“…These are totally different from the turbo-Grignard mediated polymerization of St, which can achieve full monomer conversion and low Đ at elevated temperatures rather than traditional anionic polymerization temperature of −78 °C. Meanwhile, the M n of obtained PS depends on the desired polymerization conditions, and about 11% of the turbo-Grignard reagent acts as an actual initiator (eq S1), which is similar to above MMA results and much higher than previous Barbier CARP . To understand what happens to the rest of the turbo-Grignard reagents during polymerization, PS was used as an additive and added at the beginning of polymerization, and no polymer was observed.…”

“…Meanwhile, the M n of obtained PS depends on the desired polymerization conditions, and about 11% of the turbo-Grignard reagent acts as an actual initiator (eq S1), which is similar to above MMA results and much higher than previous Barbier CARP. 55 To understand what happens to the rest of the turbo-Grignard reagents during polymerization, PS was used as an additive and added at the beginning of polymerization, and no polymer was observed. This result demonstrates that the newly formed PS at the initial stage of polymerization will interact with the turbo-Grignard reagent, resulting in inhibition of the rest turbo-Grignard reagent (Table S3, entry 2).…”

“…49−54 According to the covalent−anionic−radical characteristics of Barbier species, we recently reported a versatile Barbier covalent− anionic−radical polymerization (Barbier CARP) method capable of low Đ. 55 In the literature, Grignard reagents can initiate the anionic polymerization of polar alkene monomers such as acrylate, acrylamide, and so on, while they are not suitable for nonpolar alkene monomers (e.g., St). 22−24 Therefore, it is highly desirable to investigate turbo-Grignard reagent mediated polymerization of St through a novel polymerization mode rather than anionic polymerization.…”

“…As Grignard’s Ph.D. supervisor, Barbier reported the Barbier reaction in 1899, which can be recognized as one-pot type Grignard reaction when using magnesium as reductant . Recently, we have developed Barbier polymerization method based on the Barbier reaction and enabled the molecular design of functional polyarylamines and nonconjugated luminescent phenyl alcohol-containing polymers. − According to the covalent–anionic–radical characteristics of Barbier species, we recently reported a versatile Barbier covalent–anionic–radical polymerization (Barbier CARP) method capable of low Đ . In the literature, Grignard reagents can initiate the anionic polymerization of polar alkene monomers such as acrylate, acrylamide, and so on, while they are not suitable for nonpolar alkene monomers (e.g., St). − Therefore, it is highly desirable to investigate turbo-Grignard reagent mediated polymerization of St through a novel polymerization mode rather than anionic polymerization.…”

Up-Scale Synthesis of p-(CH2═CH)C6H4CH2CH2CH2Cl and p-ClC6H4SiR3 by CuCN-Catalyzed Coupling Reactions of Grignard Reagents with Organic Halides

“…When p -(CH 2 CH)­C 6 H 4 Cl was added dropwise to control the temperature increase, a viscous solution was obtained, indicating polymerization of the styrene moieties. It is known fact that the Grignard reagent cannot initiate the styrene polymerization, but styrene can be polymerized in a living fashion when organic halide, Mg metal, and styrene are added in one portion (Barbier-type reaction), possibly via radical or anionic intermediate species generated at the course of Grignard reagent formation . By changing THF solvent with a toluene/THF blend (75 g of p -(CH 2 CH)­C 6 H 4 Cl, 450 mL of toluene, 150 g of THF), the heat generated at the course of Grignard reagent formation was controllable.…”