Controlled/Living Radical Polymerization in the Presence of Iniferters

Abstract

Conventional free radical polymerization is limited in its inability to control polymer properties such as average molecular weight, molecular weight distribution and end-group functionality. New processes are being developed, in which the free radical propagating chain is reversibly terminated, allowing the free radical polymerization to behave in a controlled fashion. The first step in the development of controlled/living radical polymerization (C/LRP) dates back to the early 1980s when it was found that the use of iniferter (namely, agents that initiate, transfer, and terminate) systems exhibited a degree of livingness. Iniferter methodology can be used to polymerize most vinyl monomers under mild reaction conditions via thermal, redox and photochemical activations. The present chapter reviews recent advances in the use of iniferters in the C/LRP, their benefits, and current limitations. Applications of iniferters for the synthesis of telechelic polymers, complex macromolecular architectures and modification of surfaces are also discussed.

A Critical Survey of Dithiocarbamate Reversible Addition‐Fragmentation Chain Transfer (RAFT) Agents in Radical Polymerization

“…Sulfur-centered radical-mediated polymerization making use of N,N-dialkyldithiocarbamate photoiniferters or photoiniters has been reviewed by Sebenik, 43 Otsu and Matsumoto, 44 and Otsu 37 with respect to the literature through 2000, and more recently by Tasdelen and Yagci. 45 The "photoiniferter" process as originally conceived, whether with simple alkyl N,N-dialkyldithiocarbamates or dithiuram disulfides, is now little used in the synthesis of well-defined polymers. Some of the more recent examples include block 46 and star polymer syntheses.…”

“…The stability of the RAFT-adduct radical is measured using the standard radical stabilization energy (RSE). The data reported in Figure 6 15 help in understanding the difference in activity between N,N-dialkyl (44)(45)(46)(47)(48) or N-alkyl-Naryl (41)(42)(43) and those where the nitrogen is part of an aromatic ring system (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). However, a basis for discriminating between the individual members of these classes, or between these and dithiocarbamates with intermediate activity (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40), is less obvious.…”

Synthesis of hyperbranched polymers by combination of self‐condensing vinyl polymerization and iniferter process

“…Iniferter is a living/controlled radical polymerization (CRP) method that inspires its name from the initiate, transfer, and terminate terms that are taking place in the reversible activation process 19 . Although iniferter represents relatively lower control on the molecular weight distribution in comparison with other CRP procedures, it demonstrates superiority in the required polymerization temperature and purification steps 20 . Since its first introduction by Otsu in 1982, 21,22 various macromolecular architectures including homo, graft, block, star and crosslinked polymers have been synthesized via iniferter process 23–25 .…”

“…19 Although iniferter represents relatively lower control on the molecular weight distribution in comparison with other CRP procedures, it demonstrates superiority in the required polymerization temperature and purification steps. 20 Since its first introduction by Otsu in 1982, 21,22 various macromolecular architectures including homo, graft, block, star and crosslinked polymers have been synthesized via iniferter process. [23][24][25] Numerous different iniferters such as sulfides, dithiocarbamates, azo compounds and tetraphenylethanes have been reported over the years.…”

ABA triblock copolymers from two mechanistic techniques: Polycondensation and atom transfer radical polymerization

“…INTRODUCTION Using two or more mechanistic techniques is a common and effective method to generate block copolymers whose blocks provide dissimilar yet complimentary properties. [1][2][3][4][5] A classic illustration of this technique are the amphiphilic block copolymers comprised of polyethylene glycol and dendritic polyethers reported by Frechet et al in 1992. 6 Alternative procedures to unique ABA triblock copolymers use an excess of one monomer during polycondensation polymerizations which affords telechelic materials with relative ease, whose end groups may be transformed into initiating sites for a second type of polymerization.…”