A series of homologous dendronized polymers (DPs) with generations (g) 1−3 and backbone nominal degrees of polymerization (P n ) in the range 50−3000 have been synthesized and characterized in order to investigate the g-and P n -dependent viscoelastic properties and packing of this class of densely grafted, associating and effectively "thick" macromolecules in their molten state. Rheological measurements reveal an unusually long thermal equilibration time, attributed to (i) the tendency of DPs to minimize local density gradients, as realized via their mutual weak interpenetration, and (ii) the intermolecular DP−DP correlations and inter-and intramolecular hydrogen bonding and π−π stacking interactions. With the help of simulations and X-ray scattering measurements, a scenario emerges, according to which DPs interact via local cooperative rearrangements of the dendrons, akin to a Velcro fastening process. In this picture, neighboring bonds accelerate the local interpenetration process. Results from X-ray scattering show increased lateral backbone−backbone correlations with a columnar arrangement of backbones and a liquid crystalline underlying order. Linear viscoelasticity is characterized by plateau moduli which originate from intermolecular bonding and whose extent in frequency and absolute value depends on P n and g and can be lower than or comparable to that of the backbone. Very long relaxation times can be probed (sometimes via creep measurements) and attributed to the lifetime of the bonds. The nonlinear shear rheology data suggest a resemblance in behavior to unentangled linear chains with finite extensibility and point to reduced deformability of the DPs in flow. These findings indicate that DPs constitute a promising class of functional macromolecules with tunable properties.

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Two homologous series of dendronized polymers (DPs) of the second and third generations, with different degrees of polymerization of the backbone, were synthesized combining two previously reported approaches. First, methacrylate-based DPs of the first generation were prepared via radical polymerization of the corresponding methacrylate macromonomers. As the side branches of such first-generation DPs can form hydrogen bonds and π−π stacks, they are referred to as "classic" (intermolecularly interacting) DPs. Second, the first-generation DPs so prepared were grafted with branched oligoethylene glycol groups to increase the size of the dendrons up to the second and third generations. Because of the different chemical structures of the outermost generations with respect to the inner one, these DPs are termed "hybrid" DPs. The glycol-based generations do not form intermolecular supramolecular associations, which so strongly control the aging dynamics and viscoelastic properties of the interacting DPs. Therefore, the series of hybrid DPs allow for investigating the dynamics of DPs for which synergistic effects because of supramolecular interactions and topology are reduced or absent. We find, at first glance surprisingly, that the loss of intermolecular peripheral interactions increases the equilibration time dramatically. Concerning the viscoelastic behavior of the hybrids of the second generation, the onset of global relaxation is observed at low frequencies. This is in contrast with supramolecular DPs having the same generation and the same backbone degree of polymerization, for which a clear plateau region was previously demonstrated. In addition, the low-frequency plateau of the elastic modulus increases upon increase of the degree of polymerization of the backbone, suggesting that one oligoethylene generation does not suffice to completely shield supramolecular interactions between the branches. Such a scenario is also supported by atomistic simulations. The hybrid DPs of the third generation display two distinct plateau regions of the storage modulus. The first one (at higher frequencies) is of the order of 10 6 Pa, and attributed to the interpenetration of the side branches, the second is of the order of 10 3 Pa. In contrast with the behavior of second-generation hybrid DPs, the degree of polymerization of the backbone has no effect on the low-frequency plateau of third-generation hybrid DPs. This suggests that supramolecular interactions do not contribute to the elastic plateau. Hence, we ascribe it to the entanglements of the entire hybrid DPs. The reported results are summarized in a table, which compares the properties of different DPs and provides the needed ingredients for tailoring the rheology of such hyperbranched polymers.

The thermodynamic and rheological properties of densely packed dendronized polymers (DPs) at water–air interfaces were studied here for first- and fourth-generation DPs (PG1, PG4) with both small (P n ≈ 50) and large (P n ≈ 500) backbone degrees of polymerization. The excellent control over the structural characteristics of these polymers enabled us to investigate how the interfacial properties change as we go from thin, flexible macromolecules toward thicker molecular objects that display colloidal features. The effects of the dendron generation, affecting the persistence length, as well as the degree of polymerization and surface pressure on the formation of DP layers at the water–air interface were studied. Surface pressure measurements and interfacial rheology suggest the existence of significant attractive interactions between the molecules of the higher generation DPs. While all DPs featured reproducible Π–A diagrams, successive compression–expansion cycles and surface pressure relaxation experiments revealed differences in the stability of the formed films, which are consistent with the variations in shape persistence and interactions between the studied DPs. Atomic force microscopy after Langmuir–Blodgett transfer of the films displayed a nanostructuring that can be attributed to the increase in attractive forces with increasing polymer generation and anisotropy. The importance of such structures on the surface properties was probed by interfacial shear rheology, which validated the existence of strong albeit brittle structures for fourth-generation DPs. Ultimately, we demonstrate how in particular rod-like DPs can be used as robust foam stabilizers.

A series of novel quinones was synthesized by reacting tetrabromo--benzoquinone with amino oligo(ethylene glycol) dendrons of generation numbers = 0-2. According to the performed shake-flask experiments, their aqueous solubility ( = 18 mg l-1.6 g ml) and partition coefficients (log = 2.53-0.21) can be tuned in a wide range as a function of. cytotoxicity assays of tetrabromo--benzoquinone and its derivatives against MCF-7 human breast cancer cells showed a concentration- and generation-specific biological activity with IC-values as low as 0.8 μM. Further investigations revealed a considerable selectivity against cancer cells, as indicated by a weak cytotoxicity against human skin fibroblast cells (>80% survival) within the studied range of concentrations. The results demonstrate that these novel amino oligo(ethylene glycol) dendrons depict versatile tools to ameliorate physical and pharmacological characteristics of extremely hydrophobic molecules and make them susceptible to biological applications.