Fabrication of high‐strength magnetically responsive hydrogels by synergistic salting‐out and freezing–thawing and application of their shape deformation and swimming

Abstract

Smart hydrogels have been known for their remarkable applications in various fields of research. Among these smart hydrogels, magnetically responsive hydrogels are more famous because of the ease of their manipulation and a much quicker magnetic response. However, many magnetic hydrogels exhibit fragile and brittle properties. In this study, a smart combination of salting‐out and cyclic freezing–thawing was utilized for the first time to deal with sodium alginate/polyvinyl alcohol based magnetic hydrogel. The optimized magnetic hydrogel has outstanding mechanical properties with 6.66 MPa at the elongation at break of 282%, Young's modulus of 2.51 MPa, and worked with extension at fracture Wext of 9.31 MJ m−3. The magnetic hydrogel could be easily controlled by magnet, such as swim freely in water when controlled by three‐dimensional electromagnetic field. All the results show that these newly fabricated magnetic hydrogel can also carry out many difficult tasks in terms of magnetic response mechanics. This type of tough and magnetically responsive hydrogels can be used for numerous applications such as in swimming robots, flexible gripper, bionic of natural cartilage.

NIR-Mediated Deformation from a CNT-Based Bilayer Hydrogel

“…Stimuli-responsive hydrogels, also known as smart hydrogels, are materials that respond to stimuli in the external environment and undergo considerable changes in colour [ 1 , 2 , 3 ], volume [ 4 ] and mechanical properties [ 5 ]. According to different stimulus-response modes, they can be roughly divided into temperature-responsive hydrogels [ 6 ], electrical-responsive hydrogels [ 7 ], light-responsive hydrogels [ 8 , 9 ], magnetic-responsive hydrogels [ 10 , 11 , 12 ] and chemical-responsive hydrogels [ 13 , 14 ]. Because of these characteristics, they have various applications in intelligent switches [ 15 , 16 ], artificial muscles [ 17 , 18 ], soft robots [ 19 ], shape-memory materials and other fields [ 20 , 21 , 22 , 23 ].…”

NIR-mediated Deformation from a CNT-based Bilayer Hydrogel

“…Stimuli-responsive hydrogels, also known as smart hydrogels, are materials that respond to stimuli in the external environment and undergo considerable changes in colour [1][2][3], volume [4] and mechanical properties [5]. According to different stimulus response modes, they can be roughly divided into temperature-responsive hydrogels [6], electrical responsive hydrogels [7], light responsive hydrogels [8,9], magnetic responsive hydrogels [10][11][12] and chemical responsive hydrogels [13,14]. Because of these characteristics, they have various applications in intelligent switches [15,16], artificial muscles [17,18], soft robots [19], shape-memory materials and other fields [20][21][22][23].…”

Comparative Analysis of Crosslinking Methods and Their Impact on the Physicochemical Properties of SA/PVA Hydrogels

“…Furthermore, these additives can expand the range of potential hydrogel applications [16]. Another method to strengthen the mechanical properties of SA/PVA hydrogels is using a combination of processes of salting out and freezing-thawing cycles [17]. Double network structures of hydrogels also improve stretchability toughness.…”