Self-organization of dendron-poly(ethylene glycol) conjugates in an aqueous phase

Abstract

We have prepared amide dendrons having alkyl peripheral units and various focal moieties through a convergent synthetic approach. The amphiphilic properties, due to hydrophi lic amide branches and the hydrophobic peripheral units, provide an opportunity for the amide dendrons to self-organize in water. The dendritic architecture itself is also one of the critical factors in the self-organization of the amide dendrons in water. In particular, function- alization was performed at the focal point to elucidate the relationship between the focal functionality and the self-organized structures of the dendritic building blocks in the aqueous phase. The dendron having a short poly(ethylene glycol) monomethyl ether (MeO-PEG) unit (Mn = 750) as the focal moiety formed a vesicular orga- nization in water. As the size of the hydrophilic focal MeO-PEG increased to Mn = 2,000 and 5,000, the self-orga- nized structures became rod-type and spherical micelles, respectively. Our observation of multiple morphologies for amide dendrons is in good agreement with previous reports that indicated that the micellar structures changed from vesicles to rod-types and then to spheres upon increasing the size of the hydrophilic moiety of the amphiphiles.