Underwater a dhesion between model gels and functionalized surfaces: from molecular interactions to macroscopic adhesion PhD Project funded by EU ITN BIOSMARTrainee at the ESPCI ParisTech
General Informatin: Adhesion mechanisms are complex and very diverse. While the macroscopic adhesion mechanisms of soft materials in air have been extensively studied in particular by our group1 , the adhesion between two soft materials immersed in water is still relatively poorly understood, despite many applications in the biomedical and food industry for example2 . Our group has pioneered a method to measure the underwater adhesion between soft and highly swollen hydrogels and a hard surface modified with a swollen polymer brush3 . We have in particular explored in detail the effect of hydrogen bonds between polyacrylic acid and polydimethyl acrylamide as a function of contact time, pH and more recently degree of swelling.
Objective and key tasks: On the gel side, preliminary experiments with polyelectrolyte gels show that an optimum level of charging on both sides of the interface may exist for adhesion at equilibrium swelling. At very high level of ionization, the gels swell too much due to the osmotic pressure of the counterions and adhesion drops to zero even with an oppositely charged interface, while at low level of ionization the coulombic forces are too low.
On the surface side, it is possible to prepare a versatile range of surfaces with variable composition such as mixed brushes4 (with variable monomer composition in the chain or different compositions between chains). Another objective is to explore the possibility of varying the depth of the interfacial interactions between gel and polymer on the surface by creating surfaces functionalized with micron thick gels instead of simple brushes.
Objective of the PhD project
The main objective of this PhD project is to systematically explore the role of molecular and topographical changes at the interface level, on the macroscopic adhesion between a soft swollen gel and a hard functionalized surface and bridge the gap between molecular interactions and macroscopic adhesion energy. Of particular interest is the effect of pH, temperature and ionic strength and the role played by charges. The project will be carried out at the Laboratoire de Sciences et Ingénierie de la Matière Molle of the ESPCI in Paris under the supervision of Costantino Creton, Dominique Hourdet and Yvette Tran. It will also be carried out in close collaboration with the group of Alla Synytska in Dresden.
This project is part of the EU funded ITN BIOSMART Trainee which aims at developing new bioinspired surfaces for adhesive functions and applications.
Qualifications / Requirements
Ideally the candidate should have expertise in polymer chemistry, physical chemistry or polymer physics. However people with a materials science background and familiarity with mechanical testing of properties can also apply. Because of European rules the applicant cannot have spent more than 12 months in France during the last 36 months.
Last date : unspecified
Contact: Costantino Creton,
email: costantino.creton@espci.fr, dominique.hourdet@espci.fr ,
tel: +33 1 40 79 46 83