Simultaneous Photoinduced ATRP and CuAAC Reactions for the Synthesis of Block Copolymers

Abstract

Atom transfer radical polymerization (ATRP) and copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions, both utilizing copper(I) (Cu(I)) complexes, make a tremendous progress in synthetic polymer chemistry. Independently or in combination with other polymerization processes, they give access to the synthesis of polymers with well-defined structures, desired molecular architectures, and a wide variety of functionalities. Here, a novel in situ photoinduced formation of block copolymers is described by simultaneous ATRP and CuAAC processes. This approach relies on the direct reduction of initially charged copper(II) complexes to Cu(I) complexes to trigger both ATRP and CuAAC reactions coinciding under UV light at ambient temperature in one pot. Its synthetic utility is demonstrated on a model block copolymerization process by photoinduced ATRP of methyl methacrylate (MMA) using an initiator possessing acetylene functionality and concomitant click reaction between thus formed α-acetylene-poly(methyl methacrylate) (Ac-PMMA) and independently prepared azide functional polystyrene (PS-N ). Successful formation of PS-b-PMMA block copolymer is confirmed by FT-IR and H NMR spectral analysis and gel permeation chromatography (GPC) measurements.

Visible Light-Induced Atom Transfer Radical Polymerization for Macromolecular Syntheses

“…in the presence of oxygen, at room temperature or the use of catalyst at the level of parts per million (ppm). All of these methods are based on the in situ formation of activator via secondary reduction process including (I) the use of various reducing agents (either externally added (11) or monomers containing amine (12) or epoxide (13) groups as intrinsic reducing agents), (II) electrochemically redox processes (14), (III) copper-containing nanoparticles (15), and (IV) photochemically mediated redox processes (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27).…”

Photoinduced Cu(0)‐Mediated Atom Transfer Radical Polymerization

“…Among them, Cu‐based catalysts are the most widely used due to their low cost, higher efficiency, and better suitability than the others. The required Cu(I) catalysts for the ATRP process can be supplied by directly (as a Cu(I) salt such as copper bromide or chloride) or indirectly (in situ generated from either Cu(II) salts) via secondary reduction processes including: (i) the use of various reducing agents, (ii) electrochemically redox processes, and (iii) photochemically mediated redox processes . Alternatively, the Cu(I) complexes can be provided by the use of elemental copper in the form of powder or wire …”

Graft polymer growth using tandem photoinduced photoinitiator-free CuAAC/ATRP

“…They proved this system's applicability towards the preparation of homogeneous, patterned and block copolymer brushes. 48 Here, in the same line of research, we expand the scope of the one-pot approach applying combined photoinitiator-free, photoinduced ATRP and CuAAC systems towards obtaining a graft polymer in good conversion and polydispersity. [32][33][34] Some of the best known and most potent examples of click chemistry include the Diels-Alder cycloaddition, 35 thiol-ene 36 and the copper catalysed azide-alkyne cycloaddition (CuAAC).…”