The Structure And Function Regulation Of Cellulose Nanocrystal-Based Nano-assembly Materials And Their Application Exploration

Cellulose nanocrystals(CNCs)are rod-like nanoparticles with high crystallinity that could be extracted from plants or bacteria.The one-dimension characteristic and ordered arrangement of polar groups on the surface of CNC have significant spatial structure effect.This effect enables CNC to form liquid crystal structure in aqueous phase and to display controllable structural colors and photoluminescence properties when transferred to solid film,which guaranteed it high potential to be applied in accurate coding of intelligent optical sensing and anti-counterfeiting fields.Furthermore,taking advantage of the high specific surface and biocompatibility of CNC,and utilizing the controllable,orderly,and quantitative grafting of functional groups/materials on the surface of them,the high-performance separation materials based on CNC can be fabricated by carrying active adsorbent groups or materials.The dimension space of CNC makes them flexible and controllable with assembly and chemical modification,and ensure the high performance and multi-function of them by individualized design.The renewable and biodegradable of CNC also provide huge advantages of building environmental-friendly materials that could be used to replace petroleum-based materials,which is very significant for realizing sustainable development of economy and environment.However,due to the most common methods of preparing self-assembly structure are evaporation-induced method and vacuum-induced method,CNC array structural optical materials and adsorption materials generally exist in membrane structure,which leads to the limit of application form and lack of flexibility,and making it hard to be used and promoted in many fields,such as fluid optical coatings,flexible sensing device,porous separation materials with high adsorption and so on.Therefore,this study aimed at regulating and controlling the assembly of CNC under the micro-environment,and enhancing the active functional substance by effectively integrating and utilizing the spatial framework,thus obtained self-assembly materials of CNC with variable and controllable macroscopic application forms,and expand the applications of these materials in anti-counterfeiting and gas adsorption fields.The specific research content and primary progress are as follows:Firstly,metal-organic frameworks(MOFs)were used to regulate the surface charge and spatial structure of CNC,promoting the orderly assembly of CNC in the microenvironment constituted by MOF,and fixed CNC in the crystal structure of ZIF-8 to form a stable ZIF-8@CNC nanoparticle assembly structure.Through studying the interaction force between CNC and MOF in the material system,this study explored the mechanism and principle of the formation of assembly materials,and controlled the average numbers of CNC particles in MOF.Since uniaxial directional self-assembly materials of CNC possess structural color characteristics,this study explored the effect of micro-assembly on luminescence performance of materials.This strategy successfully transformed CNCbased self-assembly materials from membrane form to domain-limited nano-assembled particle,making CNC self-assembly materials obtained greater flexibility,and expanded the use form of CNC self-assembly materials,which ensured them to be better applied to paintings,ink and other optical coating coding fields.Furthermore,taking advantage of micro arrays of CNC wrapped in MOF to enhance the luminescence.Through superimposing electromagnetic field enhance mechanism into the spatial structure,carbon nano-dots(CNDs)were adsorbed into the pores of ZIF-8 in ZIF-8@CNC materials.The synergistic effects between CND,MOF and CNC were explored by adjusting the luminescence frequency of CND to study the synergistic effect of enhancing luminescence,and the change rule of luminescence intensity,luminescence quantum efficiency,and luminescence lifetime of CND@ZIF-8@CNC were interpreted.The mechanism and principle of light intensity enhancement,who were influenced by the introduction of CND,were explored with considering the extinction effect of ZIF-8 on the light intensity reduction.On the other hand,based on the specific spatial architecture formed by MOF and CNC,the high specific surface area of these two materials and the porous structure of MOF were used to enhance the adsorption performance of CNC,and applied in the ion/gas adsorption field.Through combining MOF/CNC composites with PVA aerogel to construct multi-level pore channels,the effectiveness of multistage structure for the exposure of pore channels and active sites were studied to enhance the adsorption property of materials.The spatial distribution of MOF/CNC in the PVA system and the efficient utilization of effective active sites in the system was explored,thus optimizing the gas adsorbing rate and capacity of the porous composite.According to the wide distribution pore size of the material given by this strategy,the adsorption mechanism and surface forces of multi-level porous composites were explored to further evaluate the potential of the material in practical application.Finally,the selective adsorption effect of the material on the target gas was studied by adjusting the type of pore adsorption active sites.In conclusion,this study successfully realized space control of CNC self-assembly structure in MOF nanoparticles,effectively improved the optical performance of CNC and the adsorption performance of CNC/MOF composites,and excavated the application of CNC assembly structure materials in optical anti-counterfeiting and gas adsorption.Provided theoretical guidance method for extending application forms of CNC-nanoparticle materials.