Reference : UMR5521-LAUORG-005
Workplace : GRENOBLE
Date of publication : Monday, June 20, 2022
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 September 2022
Proportion of work : Full time
Remuneration : from 2663,79 € / month, depending on the professional background
Desired level of education : PhD
Experience required : 1 to 4 years
By taking inspiration from the living world, engineers have a wide range of possibilities for designing structures capable of shape changing under the effect of external stimuli (variations in humidity, temperature, pH, light etc.). The anisotropic architecture that can be controlled and the hygro-sensitive nature of cellulosic fibrous media make papers the materials of choice for developing structures capable of substantial geometric transformations in contact with liquid water or moisture.
These transformations result from the establishment of a local gradient of hygro/hydro-expansive properties in the thickness of the material. In this project, we propose to develop papers that can take a folded 3D shape when in contact
with liquid water, based on papers that have been made hydrophobic by chromatogeny. The approach is to deactivate the hydrophobicity along lines up to a certain thickness by printing enzymes.
The objectives of the postdoct are to control the local deactivation of hydrophobicity by printing and in particular its depth of penetration in the thickness of the sheet, and then to finely characterise the self-folding phenomenon. The work will consist in particular in:
• assessing the hydroexpansive and mechanical behaviour in the wet state of the selected papers (before treatment),
• studying the influence of the deposited quantity of enzymes, the applied pressure and the time before drying on the deactivation depth,
• establishing the relationships between the deactivation depth, the hydroexpansion gradient and the folding angle when in contact with water,
• studying the kinetics of self-folding,
• developing self-folded structures of increasing complexity (accordion, then Miura-Ori).
PhD in materials science, with strong skills in multi-scale experimental characterization of fibrous media, especially bio-based. Knowledge of hygroscopic behaviour and hygro-mechanical coupling in bio-based fibrous media and/or printing processes of paper would be a plus.
The postdoct will be carried out within the PaperMorph collaborative
project, funded by the Institut Carnot Polynat (https://polynat.eu/fr). The post-doctoral fellow will work with researchers and engineers from the Laboratory of Pulp and Paper Science (LGP2, CNRS, UGA, G-INP, https://lgp2.grenoble-inp.fr), the Technical Center of Paper industry (CTP, https://www.webctp.com), the laboratory of Soils, Solids, Structures, Risks (3SR Lab, CNRS, UGA, GINP, https://3sr.univ-grenoble-alpes.fr) and the Research Centre for plant Macromolecules (CERMAV,
CNRS, UGA, https://cermav.cnrs.fr/). Location: mainly on the Grenoble University campus, 38400 Saint Martin d'Hères, France, some travel to the CTP site in Douai (59, France) will be possible.
Constraints and risks
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