Group Transfer Polymerization

Abstract

GROUP TRANSFER POLYMERIZATIONVol. 99 simplicity and robustness of controlled radical polymerizations in combination with the sensitivity of GTP to moisture and labile protons have restricted the employment of GTP for macromolecular engineering during the past 15 years. However, GTP is still attractive to several polymer synthesis research teams as it rapidly provides polymer products more homogeneous (Ð ∼1.2-1.3) than those of controlled radical polymerizations (Ð ∼1.2-1.6).The recent development of new superior catalysts for GTP provided new impetus for this polymerization method. The most noteworthy advancement was the demonstration by the groups of D. Taton (University of Bordeaux, France) and R. M. Waymouth (Stanford University, California) that NHCs equally and efficiently catalyze the GTP of acrylates, methacrylates, and acrylamides, and enable the synthesis of their block copolymers at any block sequence. Other important contributions have also been recently reported by the Groups of E. Y.-X. Chen (Colorado State University at Fort Collins, Colorado) and T. Kakuchi (Hokkaido University, Japan). Note, however, that GTP described in this article is not related to the rare earth metal-mediated group transfer polymerization developed by Yasuda in 1992 (23).This article is not intended to be a comprehensive review of GTP, but rather a brief update of an early review (24). For a complete account, the interested reader is referred to the various reviews published on the topic (25-27), and, in particular, the very recent one by Kakuchi and co-workers (28).

Metal‐Catalyzed Group‐Transfer Polymerization: A Versatile Tool for Tailor‐Made Functional (Co)Polymers

“…[3] The scope of accessible monomers for zirconocene-mediated GTP was broadened in 2004 by Mariott and Chen. They introduced highly active chiral ansa-metallocenium enolatec ations (rac-(C 2 H 4 (Ind) 2 3 ] À )f or the isoselective polymerization of methyacrylates (e.g.,m ethyland n-butylmethacrylate) and various acrylamides.T he polymerization proceeded in al iving, monometallic and intramolecular coordinative-conjugate-addition mechanism via ac yclic ester enolate intermediate (Scheme 2, right). [11d, e, 20] As sustainability is an emergingt opic in the field of macromolecular chemistry,C hen et al investigatedt he polymerization catalysis of renewable methylene butyrolactones by GTP ( Figure 1).…”

“…Therefore, this polymerization type is predestinated for the synthesis of functional polymers including block, star-and graft-copolymers ( Figure 1). [2] In this concept article, we include the term "tacticity" as ac haracteristico ff unctional polymers, since the accurate control of stereoregularity enables the design of (co)polymers with tunable glass-transition/melting temperatures associated with designed stress-strain-properties. Stereo-regular polymers often exhibit physicala nd mechanical properties superior to their stereo-random analogues.…”

“…[9 10] In GTP,t his major drawback is eliminated by the stabilizationo ft he growing chain end. [2] Therefore, GTP isl ess sensitive to temperature, allowingt op erform polymerizations at up to 100 8C. This is advantageousf rom ap ractical as well as an economicp erspective.…”

Double Networks Based on Amphiphilic Cross-Linked Star Block Copolymer First Conetworks and Randomly Cross-Linked Hydrophilic Second Networks

“…The presence of hydrophobic segments has several important implications, namely capability of swelling in organic solvents (in addition to water), lower swelling in water compared to the fully hydrophilic polymer network counterparts, and self-organization in water with the formation of hydrophobic, micelle-like, water-free domains . This self-organization may further enhance the mechanical properties of the targeted DNs. − This enhancement would be in addition to that imparted through the homogeneity of these materials which are prepared via quasi-living/controlled polymerization chemistries, including group transfer polymerization (GTP), atom transfer radical polymerization (ATRP), and reversible addition–fragmentation chain transfer (RAFT) polymerization.…”

Networks Based on “Core‐First” Star Polymers End‐Linked Using a Degradable Ketal Cross‐Linker: Synthesis, Characterization, and Cleavage

“…de ketal-containing, [21][22][23][24][25][26][27][28] dimethacrylate cross-linker to accomplish the star interconnection and/or the formation of the star core. Although the polymerizations could have been performed using a controlled radical polymerization method, [29] such as atom transfer radical polymerization or reversible addition-fragmentation radical polymerization, a type of living oxyanionic polymerization, group transfer polymerization (GTP) [30][31][32][33][34][35] was used instead. GTP is suited for the polymerization of methacrylates up to medium molecular weights, with the important advantages of operability at room temperature and very fast kinetics, requiring only 5-10 min per polymerization step.…”