Amphiphilic diblock copolymers with adhesive properties: I. Structure and swelling with water.

We study asymmetric block copolymers with the simple diblock AB architecture, in the case where the longer block A is both hydrophobic and "soft", whereas the shorter block B is hydrophilic and "hard". Materials with such a particular combination of physico-chemical and mechanical properties have distinctive advantages, in particular for designing water-compatible adhesive materials. The phase diagram is established, combining NMR and SAXS characterisations of the materials.

Force response of a viscous liquid in a probe-tack geometry: fingering versus cavitation.

We perform traction experiments on viscous liquids highly confined between parallel plates, a geometry known as the probe-tack test in the adhesion community. Direct observation during the experiment coupled to force measurement shows the existence of several mechanisms for releasing the stress: while fingering is favored for low traction velocities, low confinement and low viscosity, nucleation of bubbles occurs in the opposite conditions. It is possible to quantitatively predict the transition between the two regimes and, in many respects, describe the shape of the force response.