Rigid Urea and Self-Healing Thiourea Ethanolamine Monolayers

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• 作者：Cristina Stefaniu ; Pierre-L茅onard Zaffalon ; Alessio Carmine ; Quentin Verolet ; Samuel Fernandez ; Tomasz A. Wesolowski ; Gerald Brezesinski ; Andreas Zumbuehl
• 刊名：Langmuir
• 出版年：2015
• 出版时间：February 3, 2015
• 年：2015
• 卷：31
• 期：4
• 页码：1296-1302
• 全文大小：350K
• ISSN：1520-5827

文摘

A series of long-tail alkyl ethanolamine analogs containing amide-, urea-, and thiourea moieties was synthesized and the behavior of the corresponding monolayers was assessed on the Langmuir鈥揚ockels trough combined with grazing incidence X-ray diffraction experiments and complemented by computer simulations. All compounds form stable monolayers at the soft air/water interface. The phase behavior is dominated by strong intermolecular headgroup hydrogen bond networks. While the amide analog forms well-defined monolayer structures, the stronger hydrogen bonds in the urea analogs lead to the formation of small three-dimensional crystallites already during spreading due to concentration fluctuations. The hydrogen bonds in the thiourea case form a two-dimensional network, which ruptures temporarily during compression and is recovered in a self-healing process, while in the urea clusters the hydrogen bonds form a more planar framework with gliding planes keeping the structure intact during compression. Because the thiourea analogs are able to self-heal after rupture, such compounds could have interesting properties as tight, ordered, and self-healing monolayers.