Visible‐Light‐Driven MADIX Polymerisation via a Reusable, Low‐Cost, and Non‐Toxic Bismuth Oxide Photocatalyst

Abstract

The continuous amalgamation of photocatalysis into existing reversible deactivation radical polymerisation processes has initiated a rapidly propagating area of polymer research in recent years. We introduce bismuth oxide (Bi2O3) as a heterogeneous photocatalyst for polymerisations, operating at room temperature with visible light. We demonstrate formidable control over degenerative chain-transfer polymerisations, such as macromolecular design by interchange of xanthate (MADIX) and reversible addition-fragmentation chain transfer (RAFT) polymerisation. We achieved narrow molecular weight distributions and attribute the excellent temporal control to a photo-induced electron transfer (PET) process. This methodology was employed to synthesise diblock copolymers combining differently activated monomers. The Bi2O3 catalyst system has the additional benefits of low toxicity, reusability, low-cost, and ease of removal from the reaction mixture.

Well‐Defined, Molecular Bismuth Compounds: Catalysts in Photochemically Induced Radical Dehydrocoupling Reactions

“…Indeed, a range of inorganic bismuth compounds such as (nanostructured) oxides (Bi 2 O 3 ), [8] titanates (Bi 4 Ti 3 O 12 ), [9] vanadates (BiVO 4 ), [10] halide perovskites (Cs 3 Bi 2 Br 9 ), [11] and an oxybromide (Bi 24 O 31 Br 10 (OH) δ ) [12] have been exploited in photocatalytic transformations. Catalysed types of reactions include the degradation of organic dyes such as methyl orange, [9] antibiotics such as tetracycline, [10] and biocides such as triclosan, [8b] as well as CH activation of aliphatic and aromatic hydrocarbons, [11] transfer (de)hydrogenation of alcohols/ketones, [12] and olefin polymerisation [8a] . These applications of bismuth compounds in heterogeneous catalysis suggest that photochemical strategies might also be applicable for well‐defined, molecular bismuth compounds under homogeneous conditions.…”

An Oxygen Paradox: Catalytic Use of Oxygen in Radical Photopolymerization

“…[1] From life-sustaining cellular respiration [2] to the oxidized forms of many elements on Earth, [3] oxygen has aubiquitous role in our natural landscape.Oxygen also affects our synthetic capabilities;w hile it provides an abundant source of potential oxidants, [4] its presence can be detrimental to many reactions. [7] Other methods,s uch as the use of organoboranes or thioxanthone-anthracene photoinitiators,h ave been reported to require oxygen for the production of radicals. [7] Other methods,s uch as the use of organoboranes or thioxanthone-anthracene photoinitiators,h ave been reported to require oxygen for the production of radicals.…”

Progress and Perspectives Beyond Traditional RAFT Polymerization

“…In particular, the development of heterogeneous catalysts is receiving increasing attention, as it provides both easier separation and potential for recycling. [37][38][39][40][41][42][43][44] In parallel, computational methods are showing promise for the rational optimization of existing photocatalysts and the incorporation of new synthetic capabilities. [45,46] In addition to PET-RAFT, photoinitiators capable of directly forming radicals via homolysis under light have continued to receive attention for activating RAFT.…”