NOTE: End date changed to 12/01/2022 per NSSC information. Previous end date was 12/01/2021. (Ed., 12/2/21)

The proposed research has both fundamental and applied aspects. One of the most interesting scientific subthemes of ferromagnetism is ferrofluidics, the study and application of paramagnetic, colloidal suspensions of sub-micron size ferromagnetic particles dispersed in solvents with random orientation of the magnetic dipoles. In ferrofluids, originally developed by NASA for enabling transport of rocket propellant in space vehicles, these nano-magnets orient in applied fields, producing a bulk magnetization that in turn generates forces and torques on the host fluid. This results in a variety of exotic and useful magneto-mechanical effects, including field-induced transport and radical changes of shape, which have led to a wide variety of technical and biomedical applications. Ferromagnetic nematics combine the traditional advantages of liquid crystal ordering with permanent magnetization, leading to delicate temperature control of the intrinsic magnetic order and a facile response to applied magnetic fields that suggests a range of enhanced applications analogous to those of conventional ferrofluids. Experiments in microgravity will enable the investigation of the fundamental properties of this new family of colloidal materials and of physical phenomena that cannot easily be probed on Earth. Microgravity investigations will be carried out using the OASIS hardware in the Materials Science Glovebox on the International Space Station (ISS), with various modifications. The experiments will use the OASIS high and low resolution video cameras in their orthogonal view geometry. Magnetic freely suspended smectic bubble experiments will employ a slightly modified OASIS sample chamber. The other experiments will require new sample box designs.

NOTE: End date changed to 12/01/2022 per NSSC information. Previous end date was 12/01/2021. (Ed., 12/2/21)

The proposed research has both fundamental and applied aspects. One of the most interesting scientific subthemes of ferromagnetism is ferrofluidics, the study and application of paramagnetic, colloidal suspensions of sub-micron size ferromagnetic particles dispersed in solvents with random orientation of the magnetic dipoles. In ferrofluids, originally developed by NASA for enabling transport of rocket propellant in space vehicles, these nano-magnets orient in applied fields, producing a bulk magnetization that in turn generates forces and torques on the host fluid. This results in a variety of exotic and useful magneto-mechanical effects, including field-induced transport and radical changes of shape, which have led to a wide variety of technical and biomedical applications. Ferromagnetic nematics combine the traditional advantages of liquid crystal ordering with permanent magnetization, leading to delicate temperature control of the intrinsic magnetic order and a facile response to applied magnetic fields that suggests a range of enhanced applications analogous to those of conventional ferrofluids. Experiments in microgravity will enable the investigation of the fundamental properties of this new family of colloidal materials and of physical phenomena that cannot easily be probed on Earth. Microgravity investigations will be carried out using the OASIS hardware in the Materials Science Glovebox on the International Space Station (ISS), with various modifications. The experiments will use the OASIS high and low resolution video cameras in their orthogonal view geometry. Magnetic freely suspended smectic bubble experiments will employ a slightly modified OASIS sample chamber. The other experiments will require new sample box designs.

Field Induced Interactions of Isotropic Oil and Ferromagnetic Droplets on Smectic Films

Small droplets of paraffin oil, both neat and doped with colloidal particles of barium hexaferrite (BF), have been deposited on the surface of ultra-thin, freely suspended smectic liquid crystal films, allowing the equilibrium structures and hydrodynamics to be studied in a quasi-two-dimensional geometry. Paraffin oil droplets are observed to have both attractive forces, leading to close-packed hexagonal aggregates, as well as repulsive forces, leading to linear aggregates with well-spaced droplets. Droplet chains are observed both on uniformly thick films and along layer steps, with a droplet spacing that can be controlled, in general, with an applied electric field. Droplets doped with BF colloidal particles respond both to electric and applied magnetic fields, which induce translational motion, island formation, and changes in the droplet size.

The aggregation and chaining behavior induced by electric fields alone are significantly altered in the presence of magnetic fields. The dependence of the observed structures on electric and magnetic fields is suggestive of dipolar interactions between the droplets, while the droplet dynamics are mediated by hydrodynamic interactions with the smectic film.

NOTE: End date changed to 12/01/2022 per NSSC information. Previous end date was 12/01/2021. (Ed., 12/2/21)

The proposed research has both fundamental and applied aspects. One of the most interesting scientific subthemes of ferromagnetism is ferrofluidics, the study and application of paramagnetic, colloidal suspensions of sub-micron size ferromagnetic particles dispersed in solvents with random orientation of the magnetic dipoles. In ferrofluids, originally developed by NASA for enabling transport of rocket propellant in space vehicles, these nano-magnets orient in applied fields, producing a bulk magnetization that in turn generates forces and torques on the host fluid. This results in a variety of exotic and useful magneto-mechanical effects, including field-induced transport and radical changes of shape, which have led to a wide variety of technical and biomedical applications. Ferromagnetic nematics combine the traditional advantages of liquid crystal ordering with permanent magnetization, leading to delicate temperature control of the intrinsic magnetic order and a facile response to applied magnetic fields that suggests a range of enhanced applications analogous to those of conventional ferrofluids. Experiments in microgravity will enable the investigation of the fundamental properties of this new family of colloidal materials and of physical phenomena that cannot easily be probed on Earth. Microgravity investigations will be carried out using the OASIS hardware in the Materials Science Glovebox on International Space Station (ISS) with various modifications. The experiments will use the OASIS high and low resolution video cameras in their orthogonal view geometry. Magnetic freely suspended smectic bubble experiments will employ a slightly modified OASIS sample chamber. The other experiments will require new sample box designs.

Future work will be done to improve the measurements of field threshold as a function of filament width. Ideally, the experiments would be conducted in a zero-field environment so that background fields do not exert undue influence on the filaments, and the applied magnetic field can be calibrated reliably as a function of distance from the sample. We also plan to study the dynamics of the Fréedericksz transition and the influence of filament length on the propagation of the undulations.

The proposed research has both fundamental and applied aspects. One of the most interesting scientific subthemes of ferromagnetism is ferrofluidics, the study and application of paramagnetic, colloidal suspensions of sub-micron size ferromagnetic particles dispersed in solvents with random orientation of the magnetic dipoles. In ferrofluids, originally developed by NASA for enabling transport of rocket propellant in space vehicles, these nano-magnets orient in applied fields, producing a bulk magnetization that in turn generates forces and torques on the host fluid. This results in a variety of exotic and useful magneto-mechanical effects, including field-induced transport and radical changes of shape, which have led to a wide variety of technical and biomedical applications. Ferromagnetic nematics combine the traditional advantages of liquid crystal ordering with permanent magnetization, leading to delicate temperature control of the intrinsic magnetic order and a facile response to applied magnetic fields that suggests a range of enhanced applications analogous to those of conventional ferrofluids. Experiments in microgravity will enable the investigation of the fundamental properties of this new family of colloidal materials and of physical phenomena that cannot easily be probed on Earth. Microgravity investigations will be carried out using the OASIS hardware in the Materials Science Glovebox on International Space Station (ISS) with various modifications. The experiments will use the OASIS high and low resolution video cameras in their orthogonal view geometry. Magnetic freely suspended smectic bubble experiments will employ a slightly modified OASIS sample chamber. The other experiments will require new sample box designs.