Click graft copolymers

Li QM, Kang HL, Liu RG, Huang Y (2012) Block and hetero ethyl cellulose graft copolymers synthesized via sequent and one-pot ATRP and click reactions. Chin J Chem 30 2169-2175... 

Scheme 30.10 CuAAC click coupling of PEG-azide onto poly(propargyl glycolide) to form the water-soluble polyester graft copolymer. Reproduced with permission from Ref [82] 2008, American Chemical Society.

Figure 12.6 Schematic representation of the modular approach of synthesizing (a) block copolymers, (b) star polymers, and (c) graft copolymers by click chemistry. It should be noted that in spite of greatly enhanced ef ciency of click reactions, as compared to more conventional methods, quantitative conversion is dif cult to achieve in the case of dense grafting. (Adapted from Sumerlin and Vogt, 2010.)...

Problem 12.11 Anthracene-maleimide-based DA click reaction provides a novel route to prepare well-de ned graft copolymers. Suggest synthetic strategies involving this reaction to prepare well-de ned (a) PSt-,g-PEG and (b) PSt-g-PMMA copolymers. 

Yuan W, Li X, Gu S, Cao A, Ren J. Amphiphilic chitosan graft copolymer via combination of ROP, ATRP and click chemistry synthesis, self-assembly, thermosensitivity, fluorescence, and controlled drug release. Polymer. 2011 52 658-66. 

The copper-catalyzed azide/alkyne click reaction has found the broadest application in the modification of ROMP polymers, with the first reported example in 2004 by Binder and Kluger [13]. Since then, the copper-catalyzed click reaction has been used for the preparation of block copolymers [24, 29, 37], stars [18, 26], cycles [23], networks [25], and graft copolymers [27, 28, 38, 56, 57], as well as for end- [16] and side-chain-functionalized polymers [13, 17, 19-22, 48]. The most often used catalysts and bases for the azide/alkyne click reaction include copper(l) iodide, copper(l) bromide, trisftriphenylphosphine) copper(l) bromide, or copperfll) sulfate/sodium ascorbate as catalyst and diisopropylethylamine (DIPEA), pentamethyldiethylenetriamine (PMDETA), or 2,2 -bipyridine (bPy) as base. 

Tunca et al. [27, 28,38] reported in a series of papers on a multi-click approach for the preparation of brush copolymers. The backbone consisted of homopolymers, statistical polymers, or block copolymers from ONBEs with orthogonal side groups for Diels-Alder click reaction [27,28,38], azide/alkyne click reaction, [27, 28, 38] and nitroxide coupling [27]. In a grafting-to approach, maleimide-or ONBE-functionalized polymers (PEG, P BA, PMMA (56)) were attached by Diels-Alder click reaction with the anthracene groups pendant at the polymer backbone (55) (Scheme 9.8b). PCL chains were attached by an azide/alkyne click reaction, while a combination of Diels-Alder and azide/alkyne click reaction allowed the synthesis of graft copolymers with PS-/ -PEG-, PS-h-PMMA-, or PS-/ -P BA side chains. 

In conclusion, by overcoming the disadvantage of the previous synthetic methods for the preparation of hyperbranched polymers, we designed an all-new Seesaw-type macromonomer strategy to construct perfect hyperbranched model samples with uniform subchains. In onr stndy, we successfully prepared various kinds of Seesaw-type macromonomers, snch as homopolymers, triblock copolymers and diblock copolymers. Using these maCTomonomers as precursors, we have further prepared a series of perfect hyperbranched homopolymers, block copolymers, graft copolymers and hetero-snbchain copolymers by a combination of controlled/ living polymerization and click chemistry. Various solution properties of these novel hyperbranched (co) polymers in dilnte and semidilute solntions have been studied in detail. More specifically, the main achievements of this work are as follows ... 

Gacal, B., Durmaz, H., Tasdelen, M.A. et al. (2006) Anthracene-maleimide-based Diels-Alder click chemistry as a novel route to graft copolymers. Macromolecules, 39,5330. 

The development of PPE synthetic chemistry makes the synthesis of PPEs with various structures possible. Recently, PPE-based polymers with different topological structures including linear random copolymers, block copolymers, star polymers, miktoarm polymers, and brush and hyperbranched polymers have been synthesized. Among them, linear homopolymers or random copolymers of PPEs are perhaps the most studied. Different block copolymers with AB, ABA, and ABC architectures have been synthesized by controlled ROP. By the combination of ROP of PPE with other controlled polymerization methods, such as living radical polymerization, or click chemistry, more complex architectures including miktoarm, comb, or graft copolymers can be synthesized. The richness of structures has allowed the convenient adjustment of material properties of PPE for biomedical applications. 

Well-defined graft copolymers are most frequently prepared by either a grafting from or a grafting through controlled polymerization process however, the development of click chemistry has led to a third approach based on site-specific grafting to chemistry. 

Scheme 21 Procedure for converting distributed glycidyl functionality for a click to formation of a graft copolymer. Reprinted from Tsarevsky, N. V. Bencherif, S. A. Matyjaszewski, K. Macromolecules 2007, 40,4439-4445, with permission from the ACS.

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