Amphiphilic Dendritic Molecules:  Hyperbranched Polyesters with Alkyl-Terminated Branches

作者：Xuejing Zhai, Sergiy Peleshanko, Н. С. Клименко, Kirsten L. Genson, David Vaknin, M.Ya. Vortman, V. V. Shevchenko, Vladimir V. Tsukruk · 发表于：Macromolecules · 年份：2003 · DOI：10.1021/ma021383j · 被引用次数：77 · 研究领域：Dendrimers and Hyperbranched Polymers、RNA Interference and Gene Delivery、Polymer Surface Interaction Studies

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 cha...