Surface ordering of a perfluorinated, self-assembled, dendrimer on a water subphase

Su Rim Lee, Dong Ki Yoon, Sang Hyun Park, Eun Ho Lee, Yun Ho Kim, Patrick Stenger, Joseph A. Zasadzinski, Hee Tae Jung

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

We have investigated the surface ordering of a synthetic, asymmetric, fan-shaped dendrimer containing a carboxyl core and perfluorinated tails which was obtained by the esterification of the intermediary. X-ray diffraction patterns and transmission electron microscopy (TEM) images show the molecules self-assemble into a hexagonal, cylindrical mesophase. Surface pressure-area isotherms and Brewster angle microscopy measurements show the molecule forms a stable monolayer at the air-water interface with a single phase transition. As a condensed monolayer, the perfluorinated tails are well-packed with hexagonal symmetry with (10) spacing of ∼0.5 nm from molecular-scale atomic force microscopy (AFM) images. Such dense molecular-scale packing has not been observed in other dendritic molecules thus far. Compared to the case of conventional dendritic molecules with alkyl tails, these molecules occupy a much smaller molecular area due to the strong microphase separation between the carboxylic core and perfluorinated tails at the airwater interface. After monolayer collapse, the irregular islands with terrace morphology are observed in contrast with conventional alkyl-terminated self-assembled dendritic molecules where irregular islands do not appear. The interfacial and internal structure of every terrace shows planar columnar morphology from AFM and TEM imaging. From these results, we discuss the stability of perfluorinated, self-assembled dendrimers on water, as well as how to generate planar morphology on a hydrophilic surface.

Original languageEnglish (US)
Pages (from-to)4989-4995
Number of pages7
JournalLangmuir
Volume21
Issue number11
DOIs
StatePublished - May 24 2005

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