Assembling polymers at liquid interfaces for encapsulation

When polymer chains adsorb at liquid interfaces, they form « trains » and « loops », with a very fast adsorption/desorption dynamics between the adsorbed monomers in the « trains » and the non adsorbed monomers in the « loops ». When several polymer chains are assembled at a liquid interface, the interfacial dynamics and interfacial rheology depend on the interactions at play. Strong attractions between the layers, obtained by combining hydrogen bonds and hydrophobic interactions, hamper the adsorption/desorption dynamics and induce a building of shear and dilational viscoelasticity. The corresponding droplets can be used for encapsulation. Vanishing hydrogen interactions can be obtained by rising the pH which promotes the release and coalescence of the droplets.

Microfluidic probing of the interfacial rheology of LbL micro-capsules
Interfacial rheology on a chip

We have developped a microfluidic chip that enables to probe the interfacial tension and interfacial moduli of capsules obtained by assembling polymer molecules layer-by-layer at the oil/water interface. The capsules go through a constriction followed by an elongation chamber with an extensional flow. We  used capsules with varying interfacial tension, surface shear and compression moduli. For low interfacial moduli, the capsules may elongate after the constriction and the return to a spherical shape is driven by the interfacial tension and the elastic modulus. In some other cases, the polymer layer may rearrange in the constriction, so that the capsules « forget » their spherical shape and remain flat out of the constriction. Once in the elongation chamber, the return to a spherical shape is driven by interfacial tension but is hampered by high elastic moduli.

Collaborations: M. Reyssat (ESPCI), T. Salez (LOMA), P. Perrin (ESPCI), N. Pantoustier (ESPCI), G. Fuller (Stanford), J. Vermant (ETH)

Publications

  • « Microfluidic probing of complex interfacial rheology capsules », Tregouet, C., Salez, T., Monteux* C., Reyssat*, M., Soft Matter, 15 (13), 2782-2790, (2019) 10.1039/c8sm02507j
  • Transient deformation of a droplet near a microfluidic constriction: A quantitative analysis, Trégouët, C., Salez, T., Monteux*, C. & Reyssat*, M. Phys. Rev. Fluids3, 053603 (2018). 10.1103/PhysRevFluids.3.053603
  • Probing the adsorption/desorption of amphiphilic polymers at the air-water interface during large interfacial deformations Tregouet, C., Salez, T., Pantoustier, N., Perrin, P., Reyssat*, M., Monteux*, C., Soft Matter, (2019) 10.1039/c9sm00368a
  • Trégouët, C. et al. Adsorption dynamics of hydrophobically modified polymers at an air-water interface. Eur. Phys. J. E 41, (2018).
  • Dupré de Baubigny, J. et al. One-Step Fabrication of pH-Responsive Membranes and Microcapsules through Interfacial H-Bond Polymer Complexation. Sci. Rep. 7, (2017).
  • Le Tirilly, S. et al. Interfacial Rheology of Hydrogen-Bonded Polymer Multilayers Assembled at Liquid Interfaces: Influence of Anchoring Energy and Hydrophobic Interactions. Langmuir 32, 6089–6096 (2016).
  • Le Tirilly, S. et al. Interplay of Hydrogen Bonding and Hydrophobic Interactions to Control the Mechanical Properties of Polymer Multilayers at the Oil–Water Interface. ACS Macro Lett. 4, 25–29 (2015).