Polymerization in Aqueous Medium Using Cyclodextrin as Host Component

Abstract

Since cyclodextrins (CDs) are commercially available on a large scale they attract rapidly increasing attention in many fields of practical applications because of their ability to include several types of hydrophobic guest molecules into their cavity. They are produced in technical plants by enzymatically catalyzed modification of starch simply via degradation of helical polysaccharide into ring shaped molecules. The chemical structures of CDs are therefore derived from the repeating structural units of starch macromolecules. Thus, CDs are cyclic oligoamyloses, consisting of 6 (α), 7 (β), 8 (γ), or 9 (δ) units of 1,4-linked glucose. They exhibit a torus-shaped structure with a hydrophobic cavity and a hydrophilic outer side.^1-5 The formation of an inclusion complex leads to a significant change of the solution properties and reactivities of the guest molecules. This opens the possibility to create for example main-chain and side-chain rotaxanes from CDs as generally illustrated in Scheme 1.^6-10