From the N‐Heterocyclic Carbene‐Catalyzed Conjugate Addition of Alcohols to the Controlled Polymerization of (Meth)acrylates

Abstract

Among various N-heterocyclic carbenes (NHCs) tested, only 1,3-bis(tert-butyl)imidazol-2-ylidene (NHC(tBu) ) proved to selectively promote the catalytic conjugate addition of alcohols onto (meth)acrylate substrates. This rather rare example of NHC-catalyzed 1,4-addition of alcohols was investigated as a simple means to trigger the polymerization of both methyl methacrylate and methyl acrylate (MMA and MA, respectively). Well-defined α-alkoxy poly(methyl (meth)acrylate) (PM(M)A) chains, the molar masses of which could be controlled by the initial [(meth)acrylate]0/[ROH]0 molar ratio, were ultimately obtained in N,N-dimethylformamide at 25 °C. A hydroxyl-terminated poly(ethylene oxide) (PEO-OH) macro-initiator was also employed to directly access PEO-b-PMMA amphiphilic block copolymers. Investigations into the reaction mechanism by DFT calculations revealed the occurrence of two competitive concerted pathways, involving either the activation of the alcohol or that of the monomer by NHC(tBu) .

N‐Heterocyclic carbenes for metal‐free polymerization catalysis: an update

“…This desirable feature successfully suppresses premature crosslinking of the product. Similarly, it was recently demonstrated that MMA can be oligomerized in a more controlled manner in the presence of alcohols or hydroxyl‐functionalized polyether using 5‐tBu in DMF at 25 °C . Finally, it was also shown that dimethylacrylate (DMA) can be converted to unsaturated polyester (Scheme ) by application of TPT at 80 °C in toluene in the presence of aromatic alcohols (radical scavengers) .…”

Nickel N-heterocyclic carbene complexes and their utility in homogeneous catalysis

“…The nickel N-heterocyclic carbene complexes have also been used in the polymerization of methylmethacrylate [315] (Scheme 58). The complexes (173), (175), (178), (180), (208), (220) and (261) were effective catalysts for the polymerization of methylmethacrylate [84].…”

Chemoselective Lewis pair polymerization of renewable multivinyl-functionalized γ-butyrolactones

“…Organopolymerization [42][43][44][45] has become an important method of polymer synthesis, especially when metal-free products or processes are of main interest. For example, since the pioneering work of Hedrick and Waymouth et al [46][47][48], N-heterocyclic carbene (NHC) mediated polymerization [49][50][51][52] has advanced considerably to cover now not only the ringopening polymerization of heterocyclic monomers [53][54][55][56], but also step-growth polymerization [57][58][59], chain-growth addition polymerization of linear (acrylates, methacrylates) [60][61][62] and cyclic acrylic monomers (MMBLs) [63][64][65][66], group-transfer polymerization [67][68][69][70], Lewis pair polymerization [19][20][21][71][72][73][74][75][76] and proton-transfer polymerization [77,78]. We have recently reported the organocatalytic and chemoselective polymerization of multivinyl-functionalized γbutyrolactones, including VMBL, γ-vinyl-β-methyl-α-methylene-γ-butyrolactone and DAMBL, with NHCs [66].…”