title: Rigid urea and self-healing thiourea ethanolamine monolayers.
abstract: 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-Pockels 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.
authors.affiliation: Max Planck Institute of Colloids and Interfaces , 14476 Potsdam, Germany.
authors.forename: Cristina
authors.initials: C
authors.lastname: Stefaniu
authors.forename: Pierre-Léonard
authors.initials: PL
authors.lastname: Zaffalon
authors.forename: Alessio
authors.initials: A
authors.lastname: Carmine
authors.forename: Quentin
authors.initials: Q
authors.lastname: Verolet
authors.forename: Samuel
authors.initials: S
authors.lastname: Fernandez
authors.forename: Tomasz A
authors.initials: TA
authors.lastname: Wesolowski
authors.forename: Gerald
authors.initials: G
authors.lastname: Brezesinski
authors.forename: Andreas
authors.initials: A
authors.lastname: Zumbuehl
mesh_terms: D003198:Computer Simulation; D004983:Ethanolamines / Q000737:chemistry*; D006860:Hydrogen Bonding; D021241:Spectrometry, Mass, Electrospray Ionization; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014508:Urea / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D004983:Ethanolamines; C022203:N-acylethanolamines; D013438:Sulfhydryl Compounds; D014508:Urea