Research On The Properties Of Nanocellulose/Graphene Oxide/Poly Dopamine Bioinspired Nanocomposites

In the long history of development and elimination,the creatures have derived a variety of exquisite structures and unique properties,such as nacre with excellent mechanical properties,to adapt to the external environment and resist invasion.Recently,a series of bioinspired artificial nacre have been designed and prepared based on the layered structure of natural nacre.However,most composites have not achieved the goal of integrating strength and toughness,in other words,synergistically improving tensile strength,toughness and hardness.In addition to the ultimate pursuit of mechanical properties,multifunctionalization is also the development trend of new bioinspired materials to better adapt to their applications in aerospace,flexible energy storage equipment,supercapacitors,biomaterials,artificial bones,and tissue engineering.We focused on three types of bioinspired materials,namely mussel-bioinspired binary conductive film(P-GP),nacre-bioinspired ternary layered composites(rGO/CNF/PDA),and nanocomposites based on two biological structures(P-GCP),which achieved the goal of synergistically improving the tensile strength and toughness inspired by the layered structure of the natural nacre and the viscous protein component of marine mussels and endowed with multifunctionalization.The introduction of flexible nanocellulose has become the key to improving the strength and toughness,expanding the applications of bio-based materials in flexible batteries,supercapacitors,and other electronic devices,thereby achieving the high value utilization of wood.With the aid of AFM,SEM,EDS,FT-IR,XRD and XPS,the samples were characterized,mechanical and electrical tests were performed.Ultimately,the mechanism of strong and tough integration of bioinspired materials was revealed.The main conclusions of this research are as follows:(1)Preparation and performance of P-GP bioinspired materialsThe surface of materials deposited copper nanoparticles by immersing in Cu2+solution with the reducing agent of NaH2PO2·H2O based on the graphene oxide/polydopamine(GO/PDA)composites.The polydopamine-copper ion chelate architecture formed by the reaction can significantly improve the tensile strength,reaching 459.5 MPa,which is 2.2 times that of GO/PDA.At the same time,the toughness is 6.4 MJ/m3,which is an increase of about 60%.Moreover,the copper nanoparticles uniformly deposited on the surface of the materials can greatly improve the electrical properties.Electrical conductivity can reach up to 252.7 S·cm-1,which is 4.5 times that of rGO/PDA.(2)Preparation and properties of rGO/CNF/PDA bioinspired filmFilm with different nanocellulose content were obtained by using graphene oxide,nanocellulose and dopamine as raw materials and a vacuum-assisted filtration self-assembly process.Then rGO/CNF/PDA nanocomposites were prepared followed by copper ion treatment and HI reduction.CNF and DA entered between the nanosheets and formed hydrogen bonding and covalent bonding with GO under the certain conditions,respectively.With the introduction of nanocellulose,the tensile strength of film was as high as 528.0 MPa,which was 2.2 times that of the binary material;the toughness has reached 7.3 MJ m-3,an increase of 52%,and its superior mechanical properties were higher than other artificial nacre.However,the maximum conductivity was only 56.2 S·cm-1,which needs further exploration and optimization.(3)Preparation and properties of P-GCP artificial nacreThe GO/CNF/PDA ternary materials were obtained through vacuum-assisted self-assembly,and the polydopamine coating and copper nanoparticles deposition were performed to further prepare P-GCP artificial nacre which combined the inspiration of the two bioinspired materials mentioned above.Compared with the P-GP,the addition of nanocellulose improved the mechanical properties of the composites.Theirs tensile strength and toughness were 712.9 MPa and 7.7 MJ/m3,which were increased by 55%and 20%,respectively.Compared with rGO/CNF/PDA nanocomposites,the generation of copper nanoparticles and the construction of ionic bonding had greatly improved the material's electrical property,and their electrical conductivity has reached 194.4 S·cm-1,which was equivalent to that of rGO.