(713e) Interactions of Soft Microcapsules with a Nearby Boundary Measured Via Scattering Morphology Resolved Total Internal Refraction Microscopy (SMR-TIRM)

The adhesion and deformation of soft particles, such as red blood cells (RBCs), when interacting with a boundary can provide insights and help to identify diseases like a sickle-cell disease. A variety of other engineering applications also depend on the interaction of soft and hard surfaces. Our team investigated this phenomenon by measuring how synthetic microcapsules with an enclosed oil core and a solid polymer shell interacted with a nearby glass boundary. Microcapsules were synthesized with an established technique starting with oil-in-water Pickering emulsions containing cinnamon leaf oil stabilized by calcium carbonate nanoparticles that were subsequently polymerized through the ion exchange and cross-linking reactions under acidic environment. Capsule size and surface charge were characterized for different fabrication conditions and Scattering Morphology Resolved Total Internal Refraction Microscopy (SMR-TIRM) was utilized to measure the interaction, adhesion, and deformation with high energy and spatial sensitivity. Relative diffusion coefficients and Brownian Dynamics were analyzed and simulated to explore the physiochemical mechanism by which the capsules interacted with the wall. We found the capsules experienced a tethering or 'sticky’ potential of interaction consistent with polymer-surface interactions. Deformation was further measured and analyzed from geometry changes for adhesive soft gel response to systematically changing shear force via SMR-TIRM.