Hyperbranched polyglycerols (DP n ) 23-83; Mw/Mn ) 1.2-1.5) as well as their propoxylated derivatives were esterified to different extents (23%-100%) with various carboxylic acids (C2 to C18, benzoic, biphenylcarboxylic, and benzoic acid). Composition and molecular weight of the hyperbranched polyether scaffolds were varied with absolute molecular weights (NMR) ranging from Mn ) 1800 to 12 400 g/mol. Complete or partial esterification did not affect the narrow polydispersities of the hyperbranched polymers, which were in the range 1.2-1.5 for the esterified polyglycerol samples and 1.2-1.9 for the esterified propoxylated polyether polyols. The parameter a (fractional molecular weight increase) was introduced, which permitted to demonstrate that SEC separates the branched polymers according to hydrodynamic volume. Because of the narrow polydispersity, the samples could be studied systematically by DSC, showing that the flexibility, i.e., T g, of the hyperbranched polymers is controlled mainly by two factors: (i) the extent of hydrogen bonding and (ii) the formation of order (mesophases, crystallization), which raises the Tg. Tg's of the esterified polyether polyols were in the range -58 to -22 °C, showing the scope and limitations of tailoring the thermal properties of hyperbranched polymers by means of derivatization.

The supramolecular assembly of octyl-, hexadecyl-, and benzyl-substituted complementary tectonics based upon barbiturates (BA) and 2,4,6-triaminopyrimidines (TP) were studied in bulk, in cyclohexane, and in a polypropylene matrix. As evidenced by means of wide-angle X-ray scattering, FTIR spectroscopy, and atomic force microscopy (AFM), BA/TP assembly led to the formation of nanofibrillated superstructures, whereas the individual BA and TP components exhibited layered superstructures. Nanostructure formation resulting from BA/TP assembly in polypropylene melt accounted for nucleation of polypropylene crystallization, especially when using benzyl-substituted BA and TP derivatives instead of the corresponding n-alkyl-substituted derivatives. As a function of the benzyl ring substitution pattern it was possible to vary interlayer spacing and to influence nucleation with optimum nucleation efficiency observed for 1.61 nm spacing in the case of MeBz-BA/Bz-TP. Injection molding in the presence of MeBz-BA/Bz-TP and of Bz-BA/MeBz-TP assemblies revealed increased stiffness, as determined by Young's modulus, without sacrificing impact strength when the content of nucleating assembly was increased from 0 to 2 wt %. Transcrystallization of polypropylene onto BA/TP nanostructures was imaged by means of crossed-polarized light microscopy.

The supramolecular assembling of small amounts of octyl- and benzyl-substituted complementary tectons based upon barbiturates (BA) and 2,4,6-triaminopyrimidines (TP) was studied in a polystyrene matrix by means of differential scanning calorimetry (DSC), dynamic-mechanical spectroscopy, and transmission electron microscopy (TEM). Self-organization of these tectons within the compounds drastically changes the melt rheology in comparison to the pure matrix. Depending on external conditions such as temperature and mechanical deformation, the formation of BA/TP assemblies in polystyrene via self-organization leads to strongly increased dynamic moduli and a networklike behavior. A minimum content of 3 wt % of BA/TP is required for these rheological effects. A similar self-organization and reinforcing effect could not be observed in a more polar poly(methyl methacrylate) matrix. The resulting BA/TP structures were also examined by TEM and polarized light microscopy in both polymer matrices as well as at the interface of sandwiches consisting of PMMA and polystyrene layers. The microscopic techniques confirm the rheological results with respect to the dynamic self-organization and provide information about the concerning morphology development.