Mooney and Suo developed a new method of incorporating iron oxide particles into gels to make the gels responsive to a magnetic field. Typically, these particles are incorporated in a homogeneous manner. Varying the spatial distribution of the particle concentration to produce biphasic ferrogels results in gels that exhibit enhanced mechanical properties due to the iron oxide particle distribution. The homogeneous iron oxide distribution of monophasic ferrogels and the gradient iron oxide distribution of biphasic ferrogels are clearly demonstrated with scanning electron microscopy with energy dispersive spectroscopy showing iron in yellow and carbon in blue. Biphasic ferrogels demonstrate enhanced deformation and increased fatigue resistance, as measured by change in Young's modulus, following 4000 cycles of deformation to 50% strain.
David A. Weitz (Physics & Applied Physics)
Harvard MRSEC (DMR-1420570)