One-Pot RAFT/“Click” Chemistry via Isocyanates: Efficient Synthesis of α-End-Functionalized Polymers

Abstract

A new methodology has been developed for preparing α-functional polymers in a one-pot simultaneous polymerization/isocyanate "click" reaction. Our original synthetic strategy is based on the preparation of a carbonyl-azide chain transfer agent (CTA) precursor that undergoes the Curtius rearrangement in situ during reversible addition-fragmentation chain transfer (RAFT) polymerization yielding well-controlled α-isocyanate modified polymers. This strategy overcomes numerous difficulties associated with the synthesis of a polymerization mediator bearing an isocyanate at the R group and with the handling of such a reactive functionality. This new carbonyl-azide CTA can control the polymerization of a wide range of monomers, including (meth)acrylates, acrylamides, and styrenes (M(n) = 2-30 kDa; Đ = 1.16-1.38). We also show that this carbonyl-azide CTA can be used as a universal platform for the synthesis of α-end-functionalized polymers in a one-pot RAFT polymerization/isocyanate "click" procedure.

Synthesis of Sequence-Controlled Multiblock Single Chain Nanoparticles by a Stepwise Folding–Chain Extension–Folding Process

“…48 Isocyanates were chosen as they rapidly and quantitatively react with a wide range of nucleophiles (such as amines, thiols, alcohols, and carboxylic acids) under mild reaction conditions, without the production of a byproduct. 49 After folding of the first block, a spacer was introduced by chain extension with a nonfunctional monomer, followed by the introduction of a second foldable block, which again was folded using isocyanates. This procedure was repeated one more time to yield a penta-block consisting of three individual SCNPs each separated by a polymeric spacer representing a molecular pearl necklace.…”

Stereoregular poly(methyl methacrylate) with double-clickable ω-end: synthesis and click reaction

“…[3][4][5] From the viewpoint of polymer synthesis, to say nothing of the polyaddition via click chemistry, [6][7][8][9][10][11] polymers possessing clickable pendant groups 12,13 and/or end-functionalities [14][15][16] have attracted researchers' attention, as such polymers can be used as 'building blocks' for syntheses of highly functionalized polymers, 17,18 construction of sophisticated topology, 19,20 and surface modification 21,22 .…”

Cyclic peptide–polymer conjugates: Grafting‐to vs grafting‐from

“…6,7 In the grafting-from approach, 8,9 the polymer chains are grown from the peptide using a variety of polymerization techniques [10][11][12][13][14] while in the grafting-to approach the polymers are synthesized separately and then grafted to the peptide. [15][16][17] Fortunately, progress in conjugation chemistry has resulted in a variety of efficient reactions that are particularly useful for the functionalization of polymers, 18,19 including the well-established copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC), [20][21][22] or more traditional activated ester-mediated ligations. [23][24][25] However, despite the use of these highly efficient reactions, the grafting-to approach often requires an excess of polymer and subsequent purification of the conjugate to remove unreacted polymers.…”