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Contact and wetting properties of thin hydrogels layers

With Jessica Delavoipière, Yvette Tran and Emilie Verneuil

In collaboration with C.-Y. Hui, Cornell University

We investigate the interplay between elastic properties of thin (a few µm in the swollen state) films of hydrogel networks, their swelling state and their wetting and frictional properties based on contact and mist experiments. Model hydrogel networks are elaborated using a click-chemistry route. By playing with the chemical nature of the constituents and their structure (crosslink density), hydrogels films with varied elastic and swelling properties are synthesized.


Synthesis of model hydrogel networks using a click-chemistry route

We investigate the contribution of poroelastic drainage to indentation and frictional response of thin hydrogel layers. The approach is based on dedicated contact experiments where the water content within the gel layer confined between glass substrates is continuously monitored during the course of poroelastic drainage. Experimental results are discussed in the light of a poroelastic contact model derived within the framework of a thin film. approximation


Frictional sliding : changes in the contact shape as a function of the Pe Number defined as the ratio of the characteristic poroelastic time to the contact time. When Pe<1, the contact is at the poroelastic equilibrium which would be achieved under a purely normal loading ; when Pe>>1 the decrease in the contact size is due to the developement of a pore pressure imbalance within the out-of-equilibrium contact.

Other investigations are dealing with mist formation on these hydrogel films when cooled and submitted to an humid air.

References

J. Delavoipière, B. Hertefeu, J. Teisseire, A. Chateauminois, Y. Tran, M. Fermigier and E. Verneuil, Swelling dynamics of surface-attached hydrogel thin films in vapor flows Langmuir to appear
 

J. Delavoipière, Y. Tran, E. Verneuil, B. Herteufeu, C.-Y. Hui and A. Chateauminois
Friction of poroelastic contact with thin hydrogel layers
Langmuir 34 (2018) 9617-9626
 

Poroelastic indentation of mechanically confined hydrogel layers
J. Delavoipière, Y. Tran, E. Verneuil and A. Chateauminois
Soft Matter 12 (2016) 8049