Beta-Cyclodextrin Trimers and Adamantyl Substituted Polyacrylate Network: Synthesis and Characterization

Abstract

Polymer hydrogels are formed by networks of polymer chains that are water-soluble. Polymer hydrogels have been extensively studied because of their potential applications in a broad range of fields. Polymer network models based on the well-known β-cyclodextrin–adamantane host–guest pair has been used to obtain important insight into the interaction and controlling. Our recent studies have generated a range of hydrogels which exhibit predictable character and constitute new materials. One model are from a range of adamantane (guest) and cyclodextrin (host) substituted polyacrylates (PAA) which interact in a controlled manner. Another model of polymer network forms between adamantane (guest) substituted polyacrylates and cyclodextrin dimers (host). In this study, we synthesised b-CD trimers to act as hosts for a new polymer network model through three steps from nature b-CD and investigated the construction of novel polymer hydrogels through host-guest complexation between either 1,3,5-N,N,N-tris-(6A-deoxy- 6A-b-cyclodextrin)-benzene (bCD3bz) or 1,3,5-N,N,N-tris(6A-(2-aminoethyl)amino-6A-deoxy-6A-b- cyclodextrin)-benzene (bCDen3bz) and 3% adamantyl substituted PAA with different tether lengths. The tether attaching the adamantyl group (AD) to the poly(acrylate) backbone incorporates zero, two (en), six (hn) and twelve methylene (ddn) groups (PAAAD, PAAADen, PAAADhn and PAAADddn, respectively). Competition between the aggregation of the polymer hydrogels have been studied at the molecular level in aqueous solution by 2D NOESY 1H NMR spectroscopy and quantitatively by Isothermal Titration Calorimetry provides evidence for adamantyl group and tether linker complexation by bCD trimers and an insight into the polymer networks is gained at the macroscopic level from Rheological studies.