Bridging Ability of Telechelic Polymers Control Linked Emulsion Structure and Rheology

Telechelic polymers—polymers with functional endgroups—serve as effective rheological modifiers in colloidal suspensions, enhancing fluid strength and elasticity. In this work, we utilize the telechelic, triblock copolymer polystyrene-b-polyethylene oxide-b-polystyrene (SEOS) to induce network formation in cyclohexane-in-water emulsions. The endblocks of SEOS will partition into the droplets while the midblock remains in the continuous phase, such that each polymer chain will either loop on a single droplet or bridge between two droplets. Based on the polymer molecular weight, the endblock partition strength and the likelihood of the chains forming bridges varies. Using nonlinear rheology and confocal microscopy, we investigate the effects of these differences in polymer bridging strength and density on the emulsions’ microstructures and yielding mechanisms. We relate the yielding behavior to the heterogeneity of bridging in the system, which results from kinetic trapping and multibody effects. These findings can aid in the design of novel soft materials for applications ranging from 3D printing to biomedical scaffolds.