Correlation between superhydrophobicity and the power spectral density of randomly rough surfaces

in Langmuir (2010), 26(23), 17798-17803

We show experimentally and analytically that for single-valued, isotropic, homogeneous, randomly rough surfaces consisting of bumps randomly protruding over a continuous background, superhydrophobicity is ... [more ▼]

We show experimentally and analytically that for single-valued, isotropic, homogeneous, randomly rough surfaces consisting of bumps randomly protruding over a continuous background, superhydrophobicity is related to the power spectral density of the surface height, which can be derived from microscopy measurements. More precisely, superhydrophobicity correlates with the third moment of the power spectral density, which is directly related to the notion of Wenzel roughness (i.e., the ratio between the real area of the surface and its projected area). In addition, we explain why randomly rough surfaces with identical root-mean-square roughness values may behave differently with respect to water repellence and why roughness components with wavelength larger than 10 μm are not likely to be of importance or, stated otherwise, why superhydrophobicity often requires a contribution from submicrometer-scale components such as nanoparticles. The analysis developed here also shows that the simple thermodynamic arguments relating superhydrophobicity to an increase in the sample area are valid for this type of surface, and we hope that it will help researchers to fabricate efficient superhydrophobic surfaces based on the rational design of their power spectral density. [less ▲]

PMMA/carbon nanotube nanocomposites foams for EMI shielding application

Poster (2010, November 29)

Synthesis and characterization of reversibly cross-linked shape memory materials

Poster (2010, November 29)

Design and characterization of novel stealth Gd(II)-DOTA conjugates for magnetic resonance inaging (MRI)

Poster (2010, November 29)

Synthesis and electrografting of new functional polythiophenes onto transparent electrodes for organic solar cells

Poster (2010, November 29)

New fluorinated surfactants for nanogels preparation in supercritical CO2

Poster (2010, November 29)

Flourinated material

Patent (2010)

This invention relates to a method for modifying the surface of a material for use with a biological sample or tissue comprising the steps of providing a material having a surface which comprises reactive ... [more ▼]

This invention relates to a method for modifying the surface of a material for use with a biological sample or tissue comprising the steps of providing a material having a surface which comprises reactive-functional groups; providing fluorinated molecules having reactive-functional groups complimentary to those on the material surface; using wet chemistry to attach the fluorinated molecules to the surface of the material by reacting the reactive-functional groups of the implant with the complementary reactive-functional groups of the fluorinated molecules. The invention also relates to materials modified by said method and to implants made using said materials. [less ▲]

Macromolecular engineering to the service of advanced drug delivery systems

Conference (2010, October 25)

Multilayered chitosan-based nanofibers with antibacterial properties

Poster (2010, October 14)

Towards the synthesis of mannose derivatives of natural phenolic compounds

Poster (2010, October 14)

The aim of this project is to graft a sugar moiety onto polyfunctional natural phenolic compounds. This should enhance their water solubility. The choice of an adequate sugar such as mannose could provide ... [more ▼]

The aim of this project is to graft a sugar moiety onto polyfunctional natural phenolic compounds. This should enhance their water solubility. The choice of an adequate sugar such as mannose could provide cellular recognition. The synthesis route was first tested on cinnamyl alcohol which is structurally close to the base pattern of natural phenolic compounds. Two compounds are tested to catalyse the glycosilation between cinnamyl alcohol and D-mannose. The first one is an enzyme, the -glucosidase from almond, and the second one is a mineral acid catalyst immobilized on silica. Results show that -glucosidase is able to synthetize cinnamyl mannoside from mannose and cinnamyl alcohol. Furthermore, enzyme-catalyzed route lead to only one product and is so more specific than the chemical route where several products are observed. The obtaining of one product with a unique structure is interesting for the fundamental study of structure-function relationships (Interaction of the product with model membranes by Isothermal Titration Calorymetry and with the Langmuir Trough technique). In a future work, the reaction will be tested with more complex molecules (for example coniferyl alcohol). [less ▲]