Adhesive Tough Magnetic Hydrogels with High Fe₃O₄ Content

Abstract

Magnetic hydrogels have promising applications in flexible electronics, biomedical devices, and soft robotics. However, most existing magnetic hydrogels are fragile and suffer insufficient magnetic response. In this paper, we present a new approach to fabricate a strong, tough, and adhesive magnetic hydrogel with nontoxic polyacrylamide (PAAm) hydrogel as the matrix and the functional additive [3-(trimethoxysilyl)­propyl methacrylate coated Fe3O4] as the inclusions. This magnetic hydrogel not only offers a relatively high modulus and toughness compared to the pure hydrogel but also responds to the magnetic field rapidly because of high magnetic particle content (up to 60%, with respect to the total weight of the polymers and water). The hydrogel can be bonded to hydroxyl-rich hard and soft surfaces. Magnetic hydrogel with polydimethylsiloxane (PDMS) coating exhibits excellent underwater performance. The bonding between magnetic hydrogel and PDMS is very stable even under cyclic loading. An artificial muscle and its magnetomechanical coupling performance are demonstrated using this hydrogel. The adhesive tough magnetic hydrogel will open up extensive applications in many fields, such as controlled drug delivery systems, coating of soft devices, and microfluidics. The strategy is applicable to other functional soft materials.

Functional hydrogel coatings

“…Hydrogels also play key roles in stretchable devices and soft robotics, such as muscle-like actuators (Fig. 1 c) [ 13–15 ], hydrogel fish (Fig. 1 d) [ 16 ], soft displays [ 17 ], stretchable ionotronics (Fig.…”

Acarid Suction Cup‐Inspired Rapid and Tunable Magnetic Adhesion

“…[ 34 ] Because the saturation magnetization of iron is relatively high compared with other magnetic materials (Fe 3 O 4 66.8 emu g −1 , [ 35 ] Ni 59 emu g −1 , Co 143 emu g −1 , [ 36 ] and Fe 2 O 3 76 emu g −1[ 36 ] ), so the iron particles are chosen as the magnetic inclusions. Compared with magnetic hydrogel, [ 37 ] magnetic polymer shows a higher saturation magnetization because it is the magnetic powder rather than water to occupy most of the volume. For the iron content of 70 wt%, the maximum saturation magnetization of the sample is 133.6 emu g −1 , which is large enough.…”

Smart Materials in Regenerative Medicine

“…In addition, this kind of nanoparticles are useful in biomedical fields due to their biocompatibility and long-term stability [35]. Natural magnetic polymer hydrogels are composed of the polymer matrix and magnetic inclusions, such as magnetic Fe3O4 and γ-Fe2O3 [36]. Magnetic hydrogels have unique properties, such as rapid response and remote-control ability.…”