Supramolecular polymer networks

Lange RFM, van Gurp M, Meijer EW. Hydrogen-bonded supramolecular polymer networks. J Polym Sci Part A Polym Chem 1999 37 3657-3670. 

Fig. 24 Structure of a mechanoresptmsive metallo-supramolecular polymer network and schematic representation of (dis)assembly mechanisms, (a) Formation of (5)i j-[Eu(CI04)3] netwraks by assembly of 5 and Eu(C104)3-6H20 (C104 counterions are omitted for clarity), (b)...

Fig. 28 (a) Chemical structure of a poly(THF)-BTP polyurethane, (b) Schematic representation of structure and morphology of the metallo-supramolecular polymer network formed by combination of poly(THF)-BTP and Zn. (c) Pictures of a film of the metallo-supramolecular polymer network made from poly(THF)-BTP and Eu before and after stretching. Adapted with permission from [95]. Copyright 2013 The Royal Society of Chemistry... 

Supramolecular polymer networks combine the characteristics of chemical and physical networks and can be tailored to specific needs through the use of macro-molecular building blocks. Although they form strong materials tmder favorable... 

Supramolecular Polymer Networks Preparation, Properties, and Potential... 

Because of their transient and reversible cross-linking, supramolecular polymer networks are responsive [4] to external stimuli such as variation in temperature [31], pH [32], polarity of the solvent [33], redox reactions [34], and competitive ligation [35]. This tunability makes them useful for a plethora of applications. They can be used as drug delivery systems [36] and as matrixes in tissue engineering [37]. Drugs and cells can be encapsulated and protected within these materials and... 

Fig. 2 Different design principles for preparation of supramolecular polymer networks by heterocomplementary interactions. Cross-linking of end-capped linear chains by (a) associative nodes with a functionality higher than two or (b) additional lateral chain interactions.

The following sections describe the preparation and characterization of supramolecular polymer networks, particularly emphasizing their physical-chemical features with regard to the type and strength of physical chain cross-linking and the resulting macroscopic material properties. Furthermore, recent work on the formation and characterization of supramolecular hydrogels based on synthetic and natural precursors is summarized with a focus on their application and potential in biomedicine. 

Supramolecular Polymer Networks and Organogels 2.1 Hydrogen Bonding... 

Scheme 2 Popular metal complexation motifs used for supramolecular polymer-network formation. py pyridine, bpy bipyridine, tpy terpyridine, BTP 2,6-bis(l,2,3-triazol-4-yl)pyridine, BIP 2,6-bis(l-methylbenzimidazolyl)pyridine, DOPA dihydroxy-phenylalanine, PAA poly (acrylic acid)...

Craig and coworkers also used metallopincer complexes to form supramolecular polymer networks [143, 144]. In their work, poly(4-vinylpyridine)s were synthesized and subsequently cross-linked by addition of small-molecule bifunctional palladium(II) or platinum(II) N,C,N-pincevs in dimethyl sulfoxide. With this approach, the authors were able to control the dynamic mechanical properties of the gels, as discussed in detail in the Sect. 2.3. 

Inclusion complexation has developed to becoming another widely exploited supramolecular interaction for the formation of supramolecular polymer networks, mostly in water [197, 198]. Several classes of macrocycles have been developed, including crown ethers [199, 200], porphyrins [201, 202], cyclophanes [203], catenanes [204], cavitands [205, 206], cryptophanes [207], calix[n]arenes [208], and carcerands [209]. Macrocyclic-based supramolecular gels can either be formed from low molecular weight precursors or from macromolecular building blocks. The following discussion focuses on the latter. 

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