Multi-bridging polymers. Synthesis and behaviour in aqueous solution

We synthesized novel hydrophobically end-capped poly(N,N-dimethylacrylamide) (PDMA) star polymers of variable functionality by the RAFT procedure. The properties of these polymers in aqueous solutions were characterised by means of DLS, SANS, and rheology measurements. It was observed that they form interconnected aggregates with a correspondingly increased viscosity. Although the static structure of these systems does not depend to a larger extent on the number of hydrophobic stickers per polymer, the dynamic properties and in particular the rheological properties vary substantially with the number of arms. An increase of non-diffusive relaxation with increasing number of arms is observed by DLS and this complex dynamic behaviour is correlated to an increase of the elastic properties of the formed aggregate networks.