| Nanoellulose mainly from wood with diameters less than 100nm and lengths in the microscale, has shown impressive mechanical properties, excellent reinforcing capabilities, low weights, and low coefficients of thermal expansion, making them useful in reinforcing agents, functional films, texturing agents, and templates. However, microfibril celluloses in the primary wall are in network and high crystalized, leading to low accessibility, and difficulties of cellulose dissolution and fibrillation. Thus, high energy-consumption and low yield are main defects for regular nanocellulose preparation methods, which restricts further application of nanocellulose.Based on the knowledge of wood fiber structure and morphology, following works are conducted in this desertion, including:nanocellulose preparation, fabrication and application of nanocellulose based magnetic paper, multifunctional microfiber, and dispersant.Treatment of beating, sonication, and NaOH/urea/thiourea have been intensively studied on the influence of cellulose defibrillation. Beating results in shorter and smaller fiber, with high defibrillation degree. Sonication mainly works on the surface of cellulose, which is beneficial for the damage of the primary wall. NaOH/urea/thiourea serves to open the hydrogen bond, leadint to fiber swollen. Combining the pretreatments, highly yield nanocellulose (NFs) with excellent thermal stability was obtaine. TEMPO oxidation leads to cellulose swollen and effectively weakens the bonding between microfibrills. High stable and strong nanofibrillated cellulose (NFC) are obtained based on TEMPO oxidation and microfludizer.High transparent strong magnetic paper is fabricated by immobilization of Fe3O4 nanoparticles in an NFC network realized through mix and filtration of NFC and Fe3O4. The transmittance, tensile strength and magnetic moment of the paper can reach 86%,171.3MPa and 1.43μb respectively. It is found that high Fe3O4 loading leads to low transmittance and tensile strength but has little effect on the magnetic moment. The preparation method can be applied to make functional papers such as electrical or thermally conductive paper.Strong GO+NFC microfibers are obtained based on one-dimensional (1D) NFC and two-dimensional (2D) graphene oxide (GO) by wet spinning the GO+NFC liquid crystal solution. The microfiber strength and molecular dynamics simulations reveal synergetic effect between GO and NFC:the bonding between neighboring GO nanosheets is enhanced by NFC. Additionally, a GO nanosheet can bridge several NFC chains together, providing extra bonding sites between NFC chains over a long distance. This synergetic effect making GO+NFC microfibers are much stronger than microfibers made of NFC or GO alone. After ionic bond introduction through infiltrating, GO+NFC microfibers with a tensile strength and an elastic modulus of 442.4 MPa and 34.1 GPa respectively are obtained. The design rule investigated in this study can be universally to other structures material designs.Carbonization of the GO+NFC microfiber results in super high conductive microfiber with conductivity of 649±60 S/cm. During the carbonization, GO acted as the template for NFC carbonization, changing the morphology of carbonized NFC from microsphere to sheet and improving the carbonization of NFC. Meanwhile the coating layer of carbonized NFC can repair the vacancies and topological defects formed during GO thermal reduction and bind GO sheets together, thus further improving the conductivity. A fiber lithium ion battery was demonstrated with stable discharge capacity of 312mAh/g. The conductive microfiber obtained can be potentially applied in flexible and wearable electronics.NFC shows amphilillicty due to the presence of polar-OH groups and non-polar sites contain-CH moieties, making it an excellent dispersant and stabilizer for 2D materials (boron nitride (BN) and molybdenum disulfide (MoS2)) and ID carbon nanotube (CNT). Based on the NFC dispersed BN, MoS2, and CNT water solution, thermal conductive BN paper/film (thermal conductivity is 150W/mK, tensile strength is 182MPa), MoS2 film for Na ion battery (tensile strength of the film reaches 159MPa, first cycle capacity of the Na ion battery is 335mAh/g, after the third cycle the efficiency reaches 85%), CNT+NFC microfiber potentially for wearable electronics (tensile strength and conductivity can reach 247MPa and 266.8S/cm respectively) and strong BN microfiber (tensile strength is 244MPa) are fabricated.In this work, good results for transparent magnetic nanopaper, high conductive fibers for Li ion battery, MoS2 film for Na ion battery, thermal conductive BN film and strong BN microfiber fabrication and application based on the excellent properties of NFC, such as high mechanical strength, amphilillicty, good transparency, low CET, and stable chemical property are obtained. It is found that NFC is a excellent building block and strengthen agent for strong fibers and films. NFC is a good dispersant and stabilizer for 2D materials is revealed for the first time, which further broad the application of NFC... |
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