Structural Analysis of Hyperbranched Polymers in Solution: “Absolute” Macromolecular Characteristics and the Concept of Hydrodynamic Homology

Abstract: Macromolecules with a tree-like branching pattern represent a special class of synthetic and bio- polymers exhibiting unique structure−property relationships. The original idea in creating functional branched macromolecular systems is of course belongs to Nature, with such examples as amylopectin, dextran, glycoprotein complexes etc. First systematic studies of synthetic branched polymer systems were shown in the seminal works of Paul Flory [1]. Nowadays based on the structural/spatial organization of “monomeric units” a broad family of branched polymer systems has been established and studied. Regularly branched systems include such examples as regular star and comb/brush like copolymers. The highest level of branching symmetry can be seen in dendrimers, probably the most known example of regularly branched polymers. In solution dendrimer like macromolecules generally demonstrate arguably “perfect” hydrodynamic behavior having it roots from highly dense and compact macromolecular conformation they demonstrate. However, the dendrimers, at the same time were showed to have non-linear behavior of the intrinsic viscosity as a function of molar mass/generation number. A similar phenomenological behavior was also expected for hyperbranched macromolecules – randomly branched polymers, however, experimental results reported so far do not provide solid support for this. 
The hyperbranched macromolecules contain dendritic, linear, and terminal units and in contrast to perfectly branched dendrimers, hyperbranched have irregular macromolecular architecture. The one of the most known example could probably be hyperbranched poly(ethylene glycol)s/ polyglycerols and their copolymers. Due the large potential for biomedical and pharmaceuticals areas, these water soluble, biocompatible and easy functionalizable macromolecules are in constant focus of the both scientific and industrial communities. 
The idea of here presented research is on the one side to fill the empty spaces regarding experimentally determined/based hydrodynamic, macromolecular, and conformational characteristics of the hyperbranched polymers on the example of hyperbranched polyglycerols. [2]

On the other side, through the prism of hydrodynamic homology and the concept of hydrodynamic invariants, the complete family of branched polymer systems with respect to their size and conformation in solution will try to be standardized.

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[1] P. J. Flory, J. Am. Chem. Soc. 1941, 63, 3083-3090.

[2] (a) A. Lezov, A. Gubarev, T. Kaiser, W. Tobaschus, N. Tsvetkov, I. Nischang, U. S. Schubert, H. Frey, I. Perevyazko, Macromolecules 2020, 53, 9220-9233; (b) I. Perevyazko, J. Seiwert, M. Schömer, H. Frey, U. S. Schubert, G. M. Pavlov, Macromolecules 2015, 48, 5887-5898.