title: Interfacial stability and shape change of anisotropic endoskeleton droplets.
abstract: The delivery of suspended active ingredients to a surface is a central function of numerous commercial cosmetic, drug, and agricultural formulations. Many products use liquid droplets as a delivery vehicle but, because interfacial tension keeps droplets spherical, these materials cannot exploit the benefits of anisotropic shape and shape change offered by solid colloids. In this work, individual droplet manipulation is used to produce viscoelastic droplets that can stably retain non-spherical shapes by balancing the Laplace pressure of the liquid-liquid interface with the elasticity of an internal crystalline network. A stability criterion is developed for idealized spherocylindrical droplets and shown to agree with experimental data for varying droplet size and rheology. Shape change can be induced in the anisotropic droplets by upsetting the balance of droplet interfacial tension and internal rheology. Using dilution to increase the interfacial tension shows that external stimuli can trigger collapse and shape change in these droplets. The droplets wrap around substrates during collapse, improving contact and adhesion. The model is used to develop design criteria for production of droplets with tunable response.
authors.affiliation: Complex Fluid Microstructures, Corporate Engineering, Procter and Gamble Co, 8256 Union Center Blvd, West Chester, Ohio, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Caggioni
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Bayles
authors.forename: Jessica
authors.initials: J
authors.lastname: Lenis
authors.forename: Eric M
authors.initials: EM
authors.lastname: Furst
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Spicer
mesh_terms: D016880:Anisotropy; D004337:Drug Carriers / Q000737:chemistry*; D012212:Rheology; D013500:Surface Tension
chemical_list: D004337:Drug Carriers