Remarkable structure effects on thermoresponsive properties of dendritic macromolecules

Amphiphilic dendritic macromonomers and their corresponding dendronized polymers were synthesized, and their thermoresponsive properties investigated. These dendritic macromolecules are constructed with a second generation lysine-based dendron as the interior (hydrophobic part) and oligoethylene glycol (OEG) linear chains or dendrons (hydrophilic part) covered in their periphery. By changing from OEG linear chains to OEG dendrons, these dendritic macromolecules carry on their periphery different density of OEG moieties, to investigate the structural effects on their thermoresponsiveness. Topology of dendritic macromolecules changes through polymerization, and the fan-shaped dendritic macromonomers transfer into the corresponding cylindrically shaped dendronized polymers. Furthermore, the amphiphilic characteristic of these dendritic entities can be switched due to the thermally-induced dehydration of OEG moieties. It was found that topology, OEG density in the periphery and switchable amphiphilicity of these dendritic macromolecules show significantly effects on their thermoresponsiveness.