Synthesis of β-cyclodextrin trimers for novel polymer networks

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.1 Our recent studies have generated a range of hydrogels which exhibit predictable character and constitute new materials. They are from a range of adamantane (guest) and cyclodextrin (host) substituted polyacrylates (PAA) which interact in a controlled manner.2 Another model of polymer network forms between adamantane (guest) substituted polyacrylates and cyclodextrin dimers (host).3 In this new study, we synthesised -CD trimers to act as hosts and investigated the construction of novel polymer hydrogels through host-guest complexation between either 1,3,5-N,N,N-tris-(6A-deoxy- 6A--cyclodextrin)-benzene (CD3bz) or 1,3,5-N,N,N-tris(6A-(2-aminoethyl)amino-6A-deoxy-6A-- cyclodextrin)-benzene (CDen3bz) and 3% adamantyl substituted PAA with different tether lengths. The tether attaching the adamantyl group (AD) to the poly(acrylate) backbone incorporates two (en), six (hn) and twelve methylene (ddn) groups (PAAADen, PAAADhn and PAAADddn, respectively). Competition between the aggregation of the polymer hydrogels have been studied at the macroscopic level in aqueous solution. 2D NOESY 1H NMR spectroscopy provides evidence for adamantyl group and tether linker complexation by CD trimers and an insight into the polymer networks is gained at the macroscopic level from rheology studies.