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Study of dependence of elasticity on the microstructure of microcapsules using electro-deformation technique

Puri, Sneha, Thaokar, Rochish M.
Colloids and surfaces 2019
microstructure, models, modulus of elasticity, oils, siloxanes, strength (mechanics)
Polysiloxane microcapsules have emerged as a model system to understand capsule formation and mechanical properties, owing to the simplicity of formation. In this work, we demonstrate that the residual water in the oil phase, that also contains the precursor Octadecyl trichlorosilane (OTS), significantly affects the mechanism of formation of bigger and smaller capsules. While in larger capsules, a smooth morphology is realized, smaller capsules, on the other hand, admit hairy growth at their surface. This leads to a difference in their microstructure as well as their mechanical properties. While the bigger capsules have higher Youngs’ modulus, the smaller capsules are found to be less elastic (low Young's modulus). The kinetics of formation of capsules and their mechanical property estimation are made using a facile method, based on electrohydrodynamics, which was recently suggested by us [1,2]. The structure-property relationship demonstrated in this work should be useful in designing these microcapsules for specific applications, wherein either high or low mechanical strength is desired.