Peripheral Dendritic Functionalization Effects on the Self-Assembly and Thermoresponsive Behavior of Nonionic...

Nonionic amphiphilic block copolymers with a precise linear-dendritic architecture that exhibit thermoresponsive behavior in water are described. These copolymers consist of a hydrophilic poly-(ethylene glycol) (PEG) block connected to a thermoresponsive block based on the fourth generation of 2,2-bis-(hydroxymethyl)-propionic acid (bis-MPA) polyester dendron, functionalized at the periphery with either ureido or glycinamide groups. In water, these linear-dendritic block copolymers (LDBCs) self-assemble into different nanostructures whose size, morphology, and thermoresponse are strongly dependent on the peripheral groups and PEG chain length. The LDBC bearing peripheral ureido groups self-assembles into small micelles that, above the cloud point temperature (T _cp), evolve into a coacervate phase rather than fully dissolve. In contrast, the glycinamide-functionalized LDBCs display characteristic UCST-type behavior. The results demonstrate that subtle structural variations in the dendron periphery within a precise linear-dendritic architecture induce significant differences in the self-assembly and thermoresponse in water. Preliminary studies on the encapsulation and thermally triggered release of Nile Red, together with high cytocompatibility of these LDBCs toward several eukaryotic cell lines, suggest their potential for drug delivery systems.