title: Amphiphillic organic crystals.
abstract: The amphiphillic character, that is, the capacity to simultaneously attract and repel water, has been traditionally reserved to organic molecules such as phospholipids and surfactants, containing both hydrophilic and hydrophobic groups within the same molecule. However, this general concept can be extended to artificial structures such as micrometer-sized particles, the so-called Janus particles, and patterned surfaces. Here we provide an example of an amphiphillic crystalline solid, l-alanine, by combining atomic force microscopy measurements performed on two different cleavage surfaces showing contrasting behaviors when exposed to water vapor, with computer simulations that allow us to clarify the dipolar origin of this behavior. Although we take l-alanine as an example, our results should apply quite generally to dipolar molecular crystals.
authors.affiliation: Centre d'Investigació en Nanociència i Nanotecnologia, CIN2 (CSIC-ICN), Edifici CM7, Esfera UAB, Campus de Bellaterra, E-08193 Barcelona, Spain.
authors.forename: J J
authors.initials: JJ
authors.lastname: Segura
authors.forename: A
authors.initials: A
authors.lastname: Verdaguer
authors.forename: M
authors.initials: M
authors.lastname: Cobián
authors.forename: E R
authors.initials: ER
authors.lastname: Hernández
authors.forename: J
authors.initials: J
authors.lastname: Fraxedas
mesh_terms: D000409:Alanine / Q000737:chemistry*; D003198:Computer Simulation; D003460:Crystallization; D018625:Microscopy, Atomic Force; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D000409:Alanine