Shape Fixation of Magnetically Deformed Micropillar Arrays via Dynamic Covalent Bonds

Polymeric micropillar arrays containing magnetic particles can perform magnetic shape reconfiguration when an external magnetic field is applied. The magnetically actuated shape of micropillar arrays, however, is temporary and recover its original geometry upon removal of magnetic field. Toward the shape-fixation of actuated geometry, in this study, we employed dynamic covalent bonds for the matrix polymer of magnetic composites to provide exchange reactions in chemical networks in response to external stimuli. Magnetic deformation is achieved by the inclusion of hard magnetic particles in the polymer composites at various concentrations. We will discuss the concentration dependent structure-property relationships and optimum concentration of the magnetic particle to maximize the magnetic deformation of micropillars. Finally, we will demonstrate the thermomechanical shape fixation of magnetically actuated micropillars by constructing new chemical networks with adjacent micropillars via dynamic covalent bonds.