Supramolecular Cross-Linked Networks via Host−Guest Complexation with Cucurbit[8]uril

作者：Eric Andrew Appel, Frank H.W. Biedermann, Urs Rauwald, Samuel T. Jones, Jameel M. Zayed, Oren A. Scherman · 发表于：Journal of the American Chemical Society · 年份：2010 · DOI：10.1021/ja106362w · 被引用次数：601 · 研究领域：Supramolecular Chemistry and Complexes、Crystallography and molecular interactions、Advanced NMR Techniques and Applications

The ability to finely tune the solution viscosity of an aqueous system is critical in many applications ranging from large-scale fluid-based industrial processes to free-standing hydrogels important in regenerative medicine, controlled drug delivery, and 'green' self-healing materials. Herein we demonstrate the use of the macrocyclic host molecule cucurbit[8]uril (CB[8]) to facilitate reversible cross-linking of multivalent copolymers with high binding constants (K(a) > 10(11)-10(12) M(-2)) leading to a supramolecular hydrogel. Multivalent copolymers were prepared by free radical polymerization techniques and contained either pendant methyl viologen (a good first guest for CB[8]) or naphthoxy derivatives (good second guests for CB[8]). A colorless solution of the two multivalent copolymers bearing first and second guests, respectively, can be transformed into a highly viscous, colored supramolecular hydrogel with the cross-link density being easily controlled through CB[8] addition. Moreover, the cross-links (1:1:1 supramolecular ternary complexes of CB[8]/viologen/naphthoxy) are dynamic and stimuli-responsive, and the material properties can be modulated by temperature or other external stimuli. Rheological characterization of the bulk material properties of these dynamically cross-linked networks provided insight into the kinetics of CB[8] ternary complexation responsible for elastically active cross-linking with a second guest dissociation rate constant (k(d)) of 1200 s(-1...