Programmable Ultralight Magnets via Orientational Arrangement of Ferromagnetic Nanoparticles within Aerogel Hosts

Abstract

The actuation and levitation of air-suspended objects by a magnetic field, due to its noncontact and holonomic manipulation modes, are important technological capabilities for device applications. However, owing to a higher density of conventional ferromagnets or nanoparticle-containing polymers and strong magnetic fields required for actuation, fabricating lightweight materials with a sensitive magnetic response for weight critical applications is challenging. Here, we report ultralight aerogel-based magnets (aero-magnets) comprising assembled ferromagnetic nanomaterials with highly magnetic anisotropy where the magnetic domains can be programmed by external predesigned fields. To demonstrate the breadth of manufacturing methods for this breed of aero-magnet composites, both silica/nanocellulose aerogel hosts and ferromagnetic nanorod/nanoplatelet guests have been explored. Single and double domains with out-of-plane magnetization are programmed into the aero-magnets and characterized by magnetic force microscopy. The levitation and actuation of the aero-magnets are realized while exposed to a small external magnetic field of 11 mT and introduced to a switching circuit. Furthermore, the elastic moduli of the aero-magnets are estimated by dynamic magnetic responses of the ferromagnetic nanoparticles tightly tethered in the aerogel hosts under rapid cyclic fields. These programmable aero-magnets could serve as monolithic magnetic actuator units in the fields of tiny robots and aerospace components.

Versatile Route for Multifunctional Aerogels Including Flaxseed Mucilage and Nanocrystals

“…As magnetic nanomaterials and their composites have been investigated for biomedical, data storage, and device applications, magnetic aerogels are of great importance in various aspects of applications from microfluidic devices to electronic actuators. [ 109,110 ]…”

“…As magnetic nanomaterials and their composites have been investigated for biomedical, data storage, and device applications, magnetic aerogels are of great importance in various aspects of applications from microfluidic devices to electronic actuators. [109,110] Caffeic acid capped magnetic IONPs embedded in FSM matrix were employed to obtain ultralight magnetic porous aerogels. Figure 8 shows the TEM images of the caffeic acid capped IONPs and their size distribution (Figure 8d,e) as well as the FSM aerogel containing the magnetic NPs (Figure 8f-h).…”

Magnetic aerogel: an advanced material of high importance

“…The density was 120 mg cm −3 with a 70% porosity. 47 Considering the hyperthermia therapy application of magnetic particles, their dispersion was done into the silica matrix followed by treatment under a magnetic field to study the temperature increase. After application of 560 Oe of the magnetic field, the temperature of 45 °C was achieved.…”

Thermal Management by Engineering the Alignment of Nanocellulose

“…The combination of high visible and near‐infrared transparency, spectrally designable reflection and thermal super‐insulation was not available previously and now opens many unique opportunities in harnessing, distributing and controlling solar energy delivered to buildings. The recent progress in making aerogels with patterned magnetic domains promises [ 84 ] the possibility of magnetic “snap‐in” of aerogel films to frames of windows and other parts of building envelopes, though a significant amount of additional research and development is needed to test feasibility and effectiveness of such applications. Aerogels with intermediate and high values of haze can be also useful for daylighting solutions with even illumination of building’s interior that also combine thermal insulation with solar gain control, [ 81–83 ] which can be made from cellulose (Figure 3j–l).…”