Supramolecular polymer networks of building blocks prepared via RAFT polymerization
A novel A2B3-type supramolecular polymer network was synthesized using two precision tailored building blocks: doubly-adamantyl end-capped poly(N,N-dimethylacrylamide) and a three-pronged β-cyclodextrin (β-CD) core. The polymers were prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization yielding molecular weights between 4500 and 42600 g mol−1 and molar mass dispersities between 1.2 and 1.4. The β-CD trilinker was synthesized using a 1,3-cycloaddition of tripropargylamine and β-CD–azide. The supramolecular networks were prepared in aqueous media and the host–guest driven self-assembly of the building blocks was demonstrated via 2D nuclear Overhauser effect spectroscopy (NOESY) and dynamic light scattering (DLS). The rheological behavior of the polymer networks was investigated using steady shear and oscillatory shear measurements. Thereby, the influence of the molecular weight of the adamantyl-functionalized polymers, their concentration in aqueous solution and the ratio of adamantyl and β-CD groups on the viscosity were systematically evaluated. Additionally, the temperature dependence and the disruption of the host–guest interactions by addition of competitive native β-CD and potassium adamantyl carboxylate were exemplarily demonstrated.