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Magnetic-responsive hydrogels (MRHs) receive considerable attention in various applications owing to their smart response to an externally applied magnetic field. MRHs are typically prepared by incorporating magnetic particles into hydrogels. Their morphology and the properties, including deformation and movement, can be regulated remotely via manipulating the amplitude and direction of the applied magnetic field. For these reasons, they are considered potential materials for a range of applications, including drug delivery, regenerative medicine, environmental engineering, and soft actuators and sensors.
Despite the superior characteristics of hydrogels, including MRHs, their practical uses in biomedical fields are limited because of the weak mechanical properties and possible toxicity to the human body. In this work, the dynamic viscoelastic and magnetorheological (MR) properties of the magnetic-responsive nanocomposite hydrogels that are poly(N,N-dimethylacrylamide) (PDMAAm) hydrogels fabricated via in-situ free-radical polymerization by incorporating two different nanoparticles with different functions (Fe₃O₄ nanoparticles as magnetic substances and laponite nanoparticles as crosslinkers), called MRNCHs, have been discussed. The morphology, chemical structure, and thermal and mechanical properties of the MRNCHs were analyzed according to the weight fraction of Fe₃O₄ nanoparticles. Their viscoelastic properties, such as various moduli, and MR properties, such as relative and absolute MR effects, depending on the Fe₃O₄ nanoparticles content and applied magnetic field strengths have been investigated. Results showed that their MR properties and performances increased with increasing magnetic field strength, owing to the more robust filler network formed by the better-built alignment of Fe₃O₄ nanoparticles, and the dominant one of the reinforcing and interruption effects of nanoparticle content on the network structure determined the properties and performance of the MRNCHs. The MRNCH exhibited noticeable MR properties, excellent mechanical properties, and good biocompatibility while maintaining its high toughness, ultrastretchability, and biocompatibility holds great potential as remote-controllable soft actuators and sensors for biomedical and pharmaceutical technologies.
 

Magnetic-responsive hydrogels (MRHs), Magnetorheological (MR) property, Dynamic viscoelastic.