Amphiphilic Dendritic Molecules:  Hyperbranched Polyesters with Alkyl-Terminated Branches

Abstract

We report on the synthesis of a series of second-generation hyperbranched polyesters with a variable composition of alkyl-terminated groups. We observed that the chemical modification of the hyperbranched cores by substituting a controlled fraction of the terminal hydroxyl groups with hydrophobic alkyl chains is an effective method for a controlling amphiphilic balance of hyperbranched cores with a degree of branching of 50%. Even for imperfect cores, the chemical reaction of hydroxyl groups alkyl tails was very efficient. In fact, the number of attached alkyl tails was fairly close to the theoretical value based on the assumption that all targeted hydroxyl groups were available for the reaction despite their different interior/exterior location. Detailed microstructural analysis of the structure revealed that organized monolayers could be formed at the air-water interface if the number of alkyl tails was higher than two per core. Similar to regular dendrimers, the alkyl tails of hyperbranched molecules at high surface pressure form intramonolayer ordering of the quasi-hexagonal type. However, higher defectness and irregularities of the hyperbranched cores are responsible for poor intralayer ordering of alkyl tails in comparison with regular dendrimers. At high surface pressure, the alkyl tails became arranged in an up-right orientation. The highly water-swollen state of the hyperbranched cores of prolate shape and the partially submerged and standing-off alkyl tails is a characteristic of hyperbranched molecules with fewer alkyl chains in condensed monolayer state at the air-water interface. The core structure is transformed into the oblate, flattened state with preservation of standing-off orientation of the alkyl tails for hyperbranched molecules with crowded outer shells.

Synthesis and drug‐release properties of hyperbranched polyesters grafted with biocompatible poly(ϵ‐caprolactone)

“…HPEs (polyols with TMP as a core) were prepared by a procedure described in the literature. 20,21 Esterification was carried out at 1408C with p-TSA as an acid catalyst. The chosen molar ratio of TMP to bis-MPA was 1 : 21, corresponding to the theoretical molecular weight of 2573 g/mol and an HPE with 24 terminal hydroxyl groups.…”

Complex amphiphilic networks derived from diamine‐terminated poly(ethylene glycol) and benzylic chloride‐functionalized hyperbranched fluoropolymers

“…Driven by the desire for new types of functional polymer materials, many types of these diverse and highly‐tunable composites have been synthesized. Current areas under investigation include determination of the extent to which amphiphilic balance, architecture, and composition can mediate the properties of these amphiphilic copolymer systems 15–17…”

Assembling hyperbranched polymerics

“…[7][8][9][10][11] Highly branched polymers with cores, joints and branches, tree-like architecture, and a low level of entanglements possess different physical properties when compared with linear polymers. 12,13 Other macromolecular architectures, such as star-shaped block copolymers, have been found to exhibit interesting aggregation behavior, [14][15][16][17][18][19][20][21] which can be used for a guided formation of fluorescent nanofibers and microfibers. 22,23 The multiple terminal groups are used to control the assembly of the molecules in solution, and at surfaces and interfaces [24][25][26][27][28][29][30][31][32] as well as their stimuli-responsive behavior.…”