Functionalization of Supramolecular Polymers

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1.Construction of Supramolecular PolymersWhen a guest part was covalently attached to cyclodextrin (CD), they formed supramolecular dimers, a cyclic daisy chain, supramolecular oligomers, and polymers. t-Boc-cinnamamide-α-CD was found to form chiral supramolecular polymers in aqueous solutions. Supramolecular poly[2]rotaxane polymers and supramolecular α-, β-CD copolymers were obtained.2.Dymanics of Supramolecular PolymersWe investigated a new one-pot method to prepare polyrotaxanes containing γ-CDs by the photocyclodimerization reactions of 9-anthryl groups at the ends of the polymer chain in the presence of γ-CDs.We have constructed pseudo-rotaxanes of α-CD with axle molecules bearing pyridyl end caps via kinetic control of threading of α-CD onto axle molecules. A single substituted pyridyl group attached to the ends of the axle molecule regulated the rate for α-CD passing them. Two methyl substituents could govern the degree of complex formation of a-CD with guest molecules and resu … More lted in the distinction of face direction of CD molecules entering the axle ends. α-CDs were arranged in one direction at two station units of the axle molecule.Poly(ethylene glycol) (PEG)-substituted CDs with different chain lengths have been synthesized. PEG-substituted CDs formed self-threading complexes in aqueous solutions, and the conformational exchange dynamics between self-threading and dethreading could be regulated by its chain length.3.Polymerization of lactonesCDs were found to initiate ring-opening polymerization of some cyclic esters selectively to give a polyester with a CD at the chain end.4.Gel-to-Sol and Sol-to-Gel TransitionsUsing molecular recognition of α-CD, we have successfully constructed a photoresponsive hydrogel system by combination of simple components, α-CD, dodecyl-modified poly(acrylic acid), and a photoresponsive competitive guest, 4,4'-azodibenzoic acid. Gel-to-sol and sol-to-gel transitions occurred repeatedly by repetitive irradiations of UV and visible light. Less