Bioinspired Organization Of Inorganic Composite Monoliths

There are a large number of biominerals discovered from various natural organisms.The excellent optical and mechanical properties are due to their hierarchical structure,complex interface and special physical/chemical properties.Inspired by biominerals,researchers have learned about the relationship between hierarchical structure and function through in-depth understanding of biomaterials,and have successfully prepared many biomimetic hierarchical functional materials.In recent years,the use of renewable resources to establish sustainable platform for functional materials organization has become a critical direction in materials research.As a renewable resource,nanocellulose has attracted widespread attention due to its chirality,chemical modifiability,mechanical properties,and self-assembly properties.It is of great scientific and social significance using the intrinsic mineralization ability,auxiliary mineralization ability,assembly collaborative and biosynthetic mineralization ability of nanocellulose to organize a hierarchical nanocellulose-based inorganic composite with novel function.The current thesis draws inspiration from the biomineralization and uses the mineralization abilities of nanocellulose to expand hierarchical nanocellulose-based inorganic functional materials.In addition,this thesis discusses the mineralization ability,selectivity,mineralization process and mechanism of nanocellulose,and also explores the relationship between hierarchical structure and function,and promotes the accurate organization of function-led nanocellulose-based inorganic composites with structural hierarchy.This thesis contains five chapters.The first chapter is an introduction.Firstly,it gives an overview of biominerals,biomineralization,cellulose and nanocellulose.Subsequently,the representative nanocellulose-based inorganic composites were analyzed to summarize the mineralization ability,selectivity,mineralization methods,current research and applications of nanocellulose materials.Finally,the research purpose and significance of this thesis were explained.In the second chapter,the types of nanocellulose-based inorganic materials are further expanded.Bacterial cellulose?BC?was used as a scaffolding template,and ZACS MFI monoliths,which is three-dimensional network structure and zeolite nanoparticles stacked along the b-axis,could be obtained without additives.Firstly,BC@SiO₂ and BC@ASO precursor scaffoldings were prepared by mineralizing aluminosilicate on the surface of BC through an auxiliary mineralization strategy,and then ZACS S-1 monoliths and ZACS ZSM-5 monoliths were obtained for the first time by gas-solid phase in situ crystallization and calcination.The crystallization mechanism was proposed by tracking the crystallization process,and the morphology of the zeolite assembly was adjusted by adjusting the synthesis conditions.The larger specific surface area and tertiary connected channels of ZACS MFI are conducive to molecular diffusion.In addition,zeolite nanoparticles stacked in a single direction shows excellent adsorption selectivity,and the adsorption capacity for p-xylene is significantly higher than that for o-xylene.In the third chapter,BC@metal-organic framework composite aerogels were successfully prepared,and the types of nanocellulose-based inorganic composites were further expanded by using the intrinsic mineralization ability of BC.Firstly,the metal ions(Zn²⁺and Zr⁴⁺)were adsorbed on the surface of nanocellulose through weak interactions.Then BC@ZIF-8 and BC@UiO-66 composite aerogels with three-dimensional network structure and tertiary connected channels were obtained by ultrasonic and solvothermal synthesis methods.It is found that BC@ZIF-8 composite aerogel exhibits a low density below 0.03 g cm^-3,hierarchical porosity,large surface area,high mass transfer efficiency and superior adsorption performance of Pb²⁺and Cd²⁺.As a flexible lithium-sulfur battery interlayer,BC@UiO-66 and BC@UiO-66@PDA composite film can improve the cycling performance and reduce capacity decay rate of lithium-sulfur battery.In the fourth chapter,a chiral nematic phase cellulose nanocrystal?CNC?/SiO₂photonic crystal composite film was successfully obtained through evaporation-induced self-assembly and assembly collaborative mineralization strategy.The mesostructure of the composite film can be adjusted by adjusting the amount of TMOS and the pH of the precursor solution.After removing the CNC by calcination,a SiO₂ film with defect-related luminescence can be obtained,which retains the chiral nematic phase structure of CNC/SiO₂ photonic crystal composite film and the right-handed spiral structure of the CNC nanorods.It is found that the chiral SiO₂ film has circular polarization luminescence and dissymmetry factor is as high as-0.15,which is an ideal circular polarization luminescence material.The fifth chapter is the summary and prospect of the thesis.