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Assembly of polymers and colloids at interfaces - Cécile Monteux

Science et Ingénierie de la Matière Molle, ESPCI

The stability of foams and emulsions depends on the bulk rheological properties of the aqueous phase and on the adsorption/desorption dynamics of the molecules adsorbing at these interfaces. In the first part, I will show that mixing an amphiphilic polymer and cross linker molecules that bind reversibly to the polymer chains enables to increase both the bulk and interfacial rheological properties of the polymer transient network, leading to ultra stable foams. I will show that the foaming process of these complex fluids is controled by the non Newtonian rheological properties of the polymer network. In the second part I will focus on the adsorption dynamics of colloidal particles at interfaces with ultra low interfacial tension using fast confocal microscopy. These low interfacial tensions of the order of 100µN/m, obtained by using demixing polymer solutions, enable the observation of a capillary regime where the driving force of the particle adsorption is the unbalanced Young equation, a regime, which is usually too fast to be observed with usual liquids. At longer times, we observe a regime which is dominated by the pinning/unpinning dynamics of the contact line on the particles. I will discuss the origin of this pinning/unpinning dynamics.


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