Buckling, swelling, and catastrophic rupture of porous microcapsules
Sujit Datta (Harvard University), Alireza Abbaspourrad (Harvard University), David Weitz (Harvard University)
Complex Fluids: Suspensions, Emulsions, and Gels
Wed 1:30 - 2:50
Barus-Holley 160
Many important natural or technological situations require understanding the deformations of thin, spherical shells; examples include microcapsules for chemical encapsulation and release, biological cells, pollen grains, submersibles, and chemical storage tanks. We use microfluidics to precisely fabricate monodisperse spherical microcapsules having thin, porous, solid shells. We force the microcapsules to buckle by imposing an external osmotic pressure, and study the physics determining the onset of buckling, the dynamics of buckling, and the post-buckled shell morphologies; moreover, by carefully controlling the shell structure, we investigate how the mechanical response depends on how inhomogeneous the shells are. We also incorporate pH-responsive polymers, that become highly charged under alkaline conditions, into the microcapsule shells; by tuning the external pH, we study how the microcapsules swell, and in some cases, catastrophically rupture, under the influence of electrostatic forces.