Supramolecular graft copolymers

Figure 34.18 Supramolecular copolymer architectures, (a) AB diblock copolymer described by Hawker et a. (Reprinted with permission from Ref. [85] 2008, American Chemical Society) (b) ABC triblock copolymer described by Week et a. (Reprinted with permission from Ref [86] 2010, American Chemical Society) (c) Supramolecular graft copolymer described by Kato and Frechet. (Reprinted with permission from Ref [84] 1989, American Chemical Society) (d) Segmented copolymer described by Meijer et a. (Reprinted with permission from Ref [82] 2006, American Chemical Society.)...

Polymersomes can also be assembled from large supramolecular amphiphiles. Recently, an elegant method for the preparation of vesicles through self-assembly of supramolecular graft copolymers was developed. ... 

Figure 4.10 Supramolecular graft copolymers based on (a) UPy-DAN and (b) oligoamides achieved via ADMET polymerization.

ADMET has been used to prepare ABA triblock copolymers in conjunction with living polymerization of a-amino acid-Af-carboxyanhydrides [71]. ADMET was also used in conjunction with ATRP and chck chemistry to synthesize an amphiphilic ABCBA-type block copolymer [72]. Supramolecular graft copolymers based on 2,7-diamido- 1,8-naphthyridines have been synthesized as well [73]. These materials contained a quadruple hydrogen-bond motif in the main chain, from which a complementary hydrogen-bonding unit could be reversibly grafted. 

The effect reported in 7,88) was attributed to the higher hydrophilicity of the graft copolymers as compared to the cellulose esters. The authors did not allow for the role played by the grafted polymer structure in these reactions. At the same time, it could be interesting to investigate the conversion of cyano groups in the graft copolymer and in PAN chains isolated from the copolymer so that their supramolecular and molecular structures would remain intact. 

Such investigations performed by the authors concerned nitration of cellulose-PS graft copolymer, PS isolated from this product and PS obtained by suspension homopolymerization of styrene. The grafted PS was isolated so as to preserve its molecular mass, chemical composition and supramolecular structure104 the homopolymer was reprecipitated from benzene into methanol. The molecular mass of grafted chains was 8 x 105—106 and that of the homopolystyrene 5 x 10s. 

Supramolecular (Micro)Gels Based on Cellulose Graft Copolymers. 223... 

Keywords Aerogels Cellulose Derivatives Graft copolymers Hydrogels Physical cross-linking Supramolecular interactions... 

Jian CM, Liu BW, Chen X, Zhou ST, Fang T, Yuan JY (2014) Construction of photoresponsive supramolecular micelles based on ethyl cellulose graft copolymer. Chin J Polym Sci 32 690-702... 

More recently, the importance of introducing supramolecular interactions between macromolecular chains has become evident, and many new options have been introduced. The final step in this development would be to develop polymers based on reversible, noncovalent interactions. Rather than linking the monomers in the desired arrangement via a series of polymerization reactions, the monomers could be designed in such a way that they self-assemble autonomously into the desired stracture. As with covalent polymers, a variety of structures of these so-called supramolecular polymers are possible, with block-copolymers or graft copolymers - as well as polymer networks - being created in this way. 

By connecting polymeric blocks via a noncovalent interaction, it is possible to obtain supramolecular diblock [80], triblock [81], or multiblock copolymers [82] (Figure 34.18). Supramolecular graft polymers are also possible [83] in fact, a very early event of supramolecular polymer chemistry that actually predated the studies of Lehn was the development of side chain-functionahzed polymers by Kato and Frechet [84]. In most cases, hydrogen-bonding arrays are used, due to their strength and directionality. 

Supramolecular polymeric complexes yielding graft copolymers based on the inclusion interactions of P-cydodextrin groups in poly(N-vinyl-2-pyrrolidone-co-6-deoxy-6-methacrylate ethylamino-p-cyclodextrin) with the adamantane group on the end of PGL were also reported by Ren et... 

Rather than a first self-assembly event sucb as complexation inducing a second-order event, hierarchically stractured assemblies can also be achieved via supramolecular binding to an already self-assembled polymeric stractrue. Covalent block and graft copolymers have been extensively studied in this matmer by altering their miaophase-separated state through complexation with another macromolecule, amphiphile, or molecular host compound. 

In this chapter, an overview of hierarchically fabrication of eco-friendly supramolecular nanocomposites by means of inclusion complexation by amylose in the vine-twining polymerization was presented. The method was achieved by the phosphorylase-catalyzed enzymatic polymerization in the presence of the designed graft copolymers with guest polymeric chains. Inclusion complexation of amylose chains with guest chains in the intermolecular graft copolymers took place with the progress of the polymerization to construct the supramolecular nanocomposite... 

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