(310b) Controlling the Nonlinear Rheology of Emulsions Using Telechelic Block Copolymers

The ability to tune the rheology of materials is vital to a wide range of soft matter processing applications ranging from spray coating to additive manufacturing. Whereas linear elastic properties can be readily tuned through changes to a suspension volume fraction or through chemical additives, controlling the nonlinear yield response of materials remains a significant challenge. Here, we demonstrate that telechelic block copolymers serve as a promising method by which to induce tunable yield stresses and brittility into suspensions of emulsion droplets. We add polystyrene-b-poly(ethylene oxide)-b-polystyrene (SEOS) triblock copolymers to a suspension of cyclohexane emulsion droplets. The PS endblocks partition into droplets to form a combination of bridges and loops that build a percolating elastic network. By modifying the molecular weights of these blocks, we control the bridging fraction of the polymer and therefore the yield transition of the emulsion suspension. Furthermore, we comment on the possibility of forming brittle suspensions in which yielding results in a dramatic decrease in the viscosity of the material to enable easy processing.