Transparent Large-Strain Thermoplastic Polyurethane Magnetoactive Nanocomposites

Abstract

SummarySmart adaptive materials are an important class of materials which can be used in space deployable structures, morphing wings, and structural air vehicle components where remote actuation can improve fuel efficiency. Adaptive materials can undergo deformation when exposed to external stimuli such as electric fields, thermal gradients, radiation (IR, UV, etc.), chemical and electrochemical actuation, and magnetic field. Large strain, controlled and repetitive actuation are important characteristics of smart adaptive materials. Polymer nanocomposites can be tailored as shape memory polymers and actuators.Magnetic actuation of polymer nanocomposites using a range of iron, iron cobalt, and iron manganese nanoparticles is presented. The iron-based nanoparticles were synthesized using the soft template (1) and Sun's (2) methods. The nanoparticles shape and size were examined using TEM. The crystalline structure and domain size were evaluated using WAXS. Surface modifications of the nanoparticles were performed to improve dispersion, and were characterized with IR and TGA. TPU nanocomposites exhibited actuation for~2wt% nanoparticle loading in an applied magnetic field. Large deformation and fast recovery were www.nasa.gov 20 observed. These nanocomposites represent a promising potential for new generation of smart materials.

Magnetic Field‐Directed Self‐Assembly of Magnetic Nanoparticle Chains in Bulk Polymers

“…There is significant interest in embedding NP chains within polymers for their potentially anisotropic mechanical, electrical, optical, magnetic, and thermal properties. Diverse applications are envisioned, including actuators, artificial cilia, ferrogels, sensors, polymer solar cells, electromagnetic interference (EMI) shielding, and drug delivery …”

Morphology‐ and Phase‐Controlled Iron Oxide Nanoparticles Stabilized with Maleic Anhydride Grafted Polypropylene

“…[10] NPs with a network structure were observed ( Figure S1b) following the thermal decomposition of Fe(CO) 5 in commercial isotactic PP/xylene (weight ratio PP/Fe(CO) 5 = 1:3.5, decomposition time: 3 h). Because of the high loading and intrinsic magnetic affinity of NPs, the magnetic dipole forces are stronger than the steric repulsion forces of the polymer chains adsorbed on the NPs, hence leading to aggregates of the as-prepared NPs.…”

Self-Healing of Core–Shell Magnetic Polystyrene Nanocomposites

“…Our previously synthesized iron manganese oxide (average diameter 6.11 ± 0.69 nm) had M s , M r , and H c of 33.73 Am 2 /kg 125.1 mAm 2 /kg, and H c of 0.593 mT. 6 The size of iron cobalt oxide core manganese oxide shell nanoparticles were larger (19.49 ± 3.9 nm), exceeding the critical diameter of iron manganese oxide (9 nm) and iron cobalt oxide. The coercive force, H c shows an increase from 0.593 mT to 48.3 mT due to the iron cobalt magnetic core and a size exceeding critical superparamagnetic limit.…”