Enhancement of magnetic film with light penetration by immobilization of Fe3O4 nanoparticles in a spherical bamboo nanocellulose network

The magnetic properties of the magnetic transparent composite films largely depend on the content of Fe 3 O 4 employed. However, higher addition of Fe 3 O 4 into the matrix will lead to Fe 3 O 4 nanoparticles agglomeration resulting in the reduction in the transparency of the composite films. The contradiction between Fe 3 O 4 nanoparticle content and transparency limits the application of transparent magnetic films. In this work, the spherical bamboo nanocellulose (SBN) with an average size of 61 nm was prepared from bamboo powder by NaOH/Urea/Thiourea aqueous system, which was an effective, inexpensive and less toxic strategy. The basic structure of SBN was investigated. The SBN exhibited the cellulose II type crystal structure. The molecular chain length of SBN were lower than before dissolution. The magnetic SBN/Fe 3 O 4 composite films with light penetration were prepared. The results revealed that the dispersion of Fe 3 O 4 nanoparticles in the SBN/Fe 3 O 4 composite films was much better than that in nanofibrillated cellulose (NFC)/Fe 3 O 4 composite films because of the abundant hydrogen bonds between Fe 3 O 4 nanoparticles and SBN. The transparent results indicated the highest transmittance of the films was 94% in the wavelength range of visible light, which was almost 23.7% higher than that of NFC/Fe 3 O 4 composite films with the same amount of Fe 3 O 4 addition (15 wt%). The findings in this study also revealed that the SBN in the SBN/Fe 3 O 4 composite films was distributed in layers. The saturation magnetization of the SBN/Fe 3 O 4 composite films was 10.65 emu g −1 with 15 wt% Fe 3 O 4 incorporated, which guaranteed the excellent magnetic properties. Graphic abstract