How Can Xanthates Control the RAFT Polymerization of Methacrylates?

Abstract

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Synthesis of PMMA-based block copolymers by consecutive irreversible and reversible addition–fragmentation chain transfer polymerizations

“…The latter assumption of irreversible chain transfer is supported by the established low reactivity of S-tertiary alkyl O-ethyl xanthates in RAFT polymerization of MMA (Ctr~10 -2 ). 18 Mn,SEC determined with MALS detection and M n,theo match particularly well in the case of entry 3 of Table 1, for which the AIBN concentration is the lowest of the series. More generally, entries 1 to 5 of Table 1 4 | J.…”

“…vinyl esters and N-vinyl monomers) for the synthesis of well-defined poly(MAM)-b-poly(LAM) have gained an increasing interest. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Some groups have proposed original routes to achieve poly(MAM)-b-poly(LAM) by combining different polymerization mechanisms for each block, for example atom transfer radical polymerization (ATRP) 6 for the poly(MAM) block and reversible addition fragmentation chain transfer (RAFT) 7 polymerization for the poly(LAM) block. 8,9 The synthesis of such block copolymers by sequential monomer addition using the same polymerization mechanism is far more attractive and RDRPs based on degenerative transfer have shown the most promising results in that respect.…”

“…CTAs with intermediate reactivities, such as 3,5-dimethyl-1H-pyrazole-1-carbodithioates, have also enabled the synthesis of PDMA-b-PVAc 16 without the need for an external stimulus. Alternatively, O-ethyl xanthates, 17 fluoroxanthates 18 or N,Ndithiocarbamates 19 offer moderate control over MAMs (styrene 19 , acrylates 20 and acrylamides 21 ) and good control over LAMs. Very recently, Müllner and coworkers combined a xanthate and a bismuth oxide photocatalyst to provide excellent control over both LAMs and MAMs.…”

“…The control of the polymerization of MMA could be slightly improved by introducing halogen atoms at the 4position on the pyrazole ring, but this negatively affected the polymerization of the LAM. 23 To the best of our knowledge, there are only three examples of the synthesis of PMMA-b-PVAc by RAFT via the use of (i) switchable dithiocarbamates 12 , (ii) fluorinated xanthates in a semi-batch emulsion process, 18 or (iii) diselenocarbonate (Se-RAFT) agents. 24 however, PMMA-b-PVAc copolymers are potentially attractive to tailor interfaces in PMMA/PVAc blends 25 or to generate nanostructured phases in epoxy networks (benefiting from the miscibility of MMA block with epoxy-amine formulations).…”

Well-Defined PIII-Terminated Polymers from Phosphorylated Carbodithioate RAFT Agents

“…Several hundred of these compounds have been developed and their efficiency in RAFT polymerization has been systematically studied. Nevertheless, each CTA is suitable to control the polymerization of only a narrow range of monomers except for isolated cases like N-methyl-N-(4-pyridinyl) 14,15 and N-aryl-N-(4-pyridinyl) 16 dithiocarbamate switchable RAFT agents or CTAs of intermediate reactivity such as O-alkyl xanthates 17,18 or pyrazole-based dithiocarbamates. 19,20 A few examples of more "exotic" CTAs based on Zgroups involving other elements including heteroelements have also been described: fluorine 21 , selenium [22][23][24] , tin 25,26 or phosphorus.…”