Reconfigurable materials have been a topic of intensive scientific interest recently due to their tunability in engineering the material response to stimuli and thus their potential applications in numerous fields such as coatings and catalysts. Magnetic-field-directed assembly of nanoparticles, for example, allows for the remote control of the particles’ assembly and even structural self-repairing as well as the generation of anisotropic nanostructured materials. Polymer capillary suspension can transition from highly elastic to gel-like depending on the amount of immiscible secondary liquid. We will report how the control of the capillary forces and magnetic interactions can be used to form new smart gel systems. We will describe two types of such Magnetically Responsive Capillary Gels (MRCGs). In MRCG Type 1, the magnetic nanoparticles (MNPs) are dispersed in the liquid phase that forms capillary bridges between the polydimethylsiloxane microspheres. MRCG Type 2 is constituted of magnetically responsive elastomer microbeads with internally embedded MNPs. We will present the characterization of these gels in terms of rheology, magnetic response, and the ability to self-repair. This ongoing research demonstrates how capillary forces can be used as a basis for magnetically-directed assembly of magneto-capillary gels. We were able to show operational capillary bridging forces at a dense gel scale and demonstrated that an external magnetic field could direct the aggregation of the system through a magnetic response. We established that the formation of capillary bridges between PDMS microbeads via the addition of a secondary, immiscible fluid will lead to gel-like behavior. We proved that both MRCGs exhibit the property of magnetic-field-induced self-repair. We characterized the properties of the gels with respect to rheology, magnetic properties, and ability to re-assembly application. We will discuss how these gels can be used in the formulation and testing of new classes of soft, responsive, and multifunctional matter.

Formulation of new responsive and self-repairing magneto-capillary gels

2019 Fall National Meeting

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