Multifunctional thermal regulation materials with good thermal properties, efficient magnetic performance, and satisfactory interface bonding on fabrics are highly desirable for protective fabrics, building winter protection materials, medical thermal regulation materials, and special-environment work clothing. Herein, a new class of magnetic phase-change PW@CaCO₃@Fe₃O₄ microcapsules was successfully produced by controlling the content of magnetic Fe₃O₄ through a self-assembly method. The microstructure, chemical composition, phase-change behavior, and magnetic properties of the products were sequentially characterized and analyzed. The findings revealed that the obtained microcapsules possessed regular spherical structure with uniform size and excellent thermal properties. Furthermore, PW@CaCO₃ with Fe₃O₄ (i.e., 8% mass fraction) showed the highest thermal regulation and magnetic properties and reached an enthalpy value of 94.25 J·g⁻¹, which is clearly superior to the value of 77.51 J·g⁻¹ for PW@CaCO₃ microcapsules. At the same time, the encapsulation efficiency of 38.7% and saturation magnetization of 2.50 emu·g⁻¹ were the best among the four given samples. Therefore, the good paramagnetic feature had a significant synergistic effect on the thermal properties of the PW@CaCO₃ microcapsules under study. More importantly, multifunctional fabrics loaded with PW@CaCO₃@Fe₃O₄ microcapsules still showed an enthalpy value of 25.81 J·g⁻¹ after several washes and have the potential to be used widely in the field of temperature control. The thermal regulation fabrics in this study exhibited excellent thermal properties and fastness, which contribute to their practical applications in advancing multifunctional textiles and high-technology modern fabrics.

Magnetic protective fabrics with fine wearability and great protective properties are highly desirable for aerospace, national defense, and wearable protective applications. The study of the controllable preparation method of Nd³⁺ doped in Fe₃O₄ nanoparticles with supposed magnetic properties remains a challenge. The characterization of the microstructure, elemental composition, and magnetic properties of NdFe₂O₄ nanoparticles was verified. Then, the surface of NdFe₂O₄ was treated with glyceric acid to provide sufficient –OH. Subsequently, the connection of the nanoparticle by the succinimide group was studied and then grafted onto cotton fabrics as its bridging effect. The optimal loading rate of the functional fabrics with nanoparticles of an average size of 230 nm was 1.37% after a 25% alkali pretreatment. The color fatness to rubbing results showed better stability after washing and drying. The corresponding hysteresis loop indicated that the functional fabrics exhibited typical magnetism behavior with a closed “S” shape and a magnetic saturation value of 17.61 emu.g⁻¹ with a particle size of 230 nm. However, the magnetic saturation value of the cotton fabric of 90 nm was just 4.89 emu.g⁻¹, exhibiting controllable preparation for the aimed electromagnetic properties and great potential in radiation protective fields. The electrochemical properties of the functional fabrics exhibited extremely weak electrical conductivity caused by the movement of the magnetic dipole derived from the NdFe₂O₄ nanoparticles.

In order to enhance the application of thermoregulated materials, magnetic phase change microcapsules were prepared using a self-assembly method. Paraffin wax was chosen for its fine thermoregulation properties as the core material, while Fe₃O₄ nanoparticles doped in calcium carbonate served as the hybrid shell material. The microcapsules were then blended with sodium alginate and processed into seaweed fibers through wet spinning. The microstructure, thermal, and magnetic properties of the microcapsules were analyzed using scanning electron microscopy, energy dispersive X-ray spectroscopy, a laser particle size analyzer, an X-ray diffractometer, a differential scanning calorimeter, a thermogravimetric analyzer, and a vibrating sample magnetometer. The thermoregulation of the fibers was evaluated using a thermal infrared imager. The results indicated that the microcapsules had a uniform size distribution and good thermal properties. When the mass fraction of Fe₃O₄ nanoparticles was 8%, the microcapsules exhibited a saturation magnetization of 2.44 emu/g and an enthalpy value of 94.25 J/g, indicating effective phase change and magnetic properties. Furthermore, the thermoregulated seaweed fibers showed a high enthalpy value of 19.8 J/g with fine shape, offering potential for developing multifunctional fiber products.