Magnetic actuators, which use magnetic effects for actuation, are very useful in many areas, such as electrical equipment, soft robots, and medical instruments. However, they inevitably suffer damage during long-term use, leading to mechanical failure. Introduction of the self-healing concept can solve this problem to a certain extent and extend their service life. Herein, a room-temperature self-healing magnetic nanocomposite is obtained using a simple, efficient, and environmental-friendly strategy. In the authors' design, soft poly(dimethylsiloxane) (PDMS) polymeric materials are chosen as the matrix, and Fe 3 O 4 nanoparticles are utilized as a functional magnetic nanofiller to obtain a new magnetic nanocomposite. By balancing the self-healing property and mechanical performance, the optimal content of magnetic filler is determined to be 15 wt%. The optimized sample exhibits an ultimate tensile strength (0.44 MPa), a high tensile strain (400%), and an excellent self-healing efficiency (62.2% mechanical recovery of fracture strength) at 25 °C for 30 min. Furthermore, this composite material shows an excellent and healable magnetic actuation performance. This new nanocomposite provides great potential for the magnetic actuation application.
Zhenzhen Yang,Renliang Huang,Wei Qi,Liping Tong,Rongxin Su,Zhimin He
Reduced graphene oxide functionalized with magnetic Fe 3 O 4 nanoparticles and –PhSO 3 H groups (Fe 3 O 4 -RGO-SO 3 H) was reported for environmentally benign hydrolysis of cellulosic materials, which is an important process in integrated utilization of biomass resource. Except for –PhSO 3 H groups, –COOH and –OH groups derived from graphene oxide (GO) were also expected in the structure of Fe 3 O 4 -RGO-SO 3 H. Fe 3 O 4 -RGO-SO 3 H exhibited outstanding catalytic performance for the hydrolysis of cellulosic materials, due to its crumpling feature with clear layers and the coexistence of –COOH and –OH groups. The unique structure of Fe 3 O 4 -RGO-SO 3 H favors the accessibility of cellulose to the active sites of the material and facilitates the diffusion of the product molecules. –COOH groups on the surface of the material provide a large concentration of acidic functionality for hydrolyzing cellulose, while –OH groups readily adsorb cellulose through forming strong hydrogen bonds between –OH groups and the oxygen atoms in β-1,4 glycosidic bonds. Furthermore, Fe 3 O 4 -RGO-SO 3 H can also be easily separated from the reaction residue with an extra magnetic force and further used at least five times.
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