| The research of green biomass materials has been extended to the scale of micrometer and nanometer.Among them,cellulose is the earliest researched,the most closely related to humans and the most abundant natural polymer resource,making it the most promising green and adjustable resource.One of the materials.However,how to match and combine the component advantages of cellulose-based materials with the structural advantages of natural materials to design and prepare high-performance and large-size bionic structural materials for practical applications is still a huge challenge.Aiming at the application requirements and development trend of dopamine in bionic mussels,this paper studies the performance optimization and application potential of dopamine on carboxymethyl cellulose from the perspective of functional modification.Focusing on this key scientific issue,this thesis starts with the control of carboxymethyl cellulose motifs,uses dopamine grafted modified carboxymethyl cellulose as the motif,and performs one-dimensional fiber based on the controllable preparation of motifs.Two-dimensional film,three-dimensional gel and other macroscopic bodies,and these materials are applied to the fields of mechanics,sensing and drug delivery.On the basis of controllable equipment,it focuses on studying the essential laws between the structure and performance of materials,and analyzes the new structural material interface of engineering structure performance.The main research conclusions are as follows:(1)Using the adhesiveness of dopamine,explored and developed biomimetic multifunctional carboxymethyl cellulose composite conjugated dopamine,using self-assembly and layering strategies to intercalate and assemble with montmorillonite to generate a layered nanocomposite film.Under the condition of relative humidity as high as 90%,the tensile strength(162.0 MPa)and elastic modulus(8.7 GPa)of the composite material are significantly improved.Thermogravimetric analysis and standard flame test also show that the nanocomposite has high thermal stability and can self-extinguish immediately after the flame(1750°C)burns.This bionic design strategy provides a feasible solution for the preparation of bionic composite materials with excellent moisture resistance and flame retardancy,and has huge application potential in tissue engineering,flexible display and outdoor shielding materials.(2)Taking advantage of the p H responsiveness of dopamine,a new type of carboxymethyl cellulose-based hydrogel was successfully constructed by cross-linking dopamine-modified carboxymethyl cellulose and cystamine.Dynamic metal/catechol complexes and disulfide bonds coexist in the hydrogel network,allowing them to interact dynamically under both environmental changes.When exposed to changes in p H or redox or both,the hydrogel exhibits a reversible sol-gel transition,resulting in a controlled release of model agrochemicals.Compared with the single trigger condition,the cumulative release of the hydrogel containing 50 m M reducing agent in the buffer at p H 5 doubled,which indicates that the common trigger condition can promote the model agriculture in the hydrogel.The release of chemicals.Due to the reversible cross-linked network,excellent biodegradability and biocompatibility of hydrogels,the efficient and sustainable cellulose-based hydrogels developed in this work are expected to provide a variety of applications in the fields of agriculture and biomedicine.application.(3)A strategy of intermolecular self-assembly is proposed,which uses dopamine-doped carbon nanotubes to modify carboxymethyl cellulose,and through wet spinning in non-solvent ethanol,a super-tough,Moisture resistant conductive fiber.In this continuous wet spinning process,directional hydrogen bonds and strong interactions between fibers are formed inside the fibers.Under high humidity conditions(90%RH),the fiber has good toughness(?76.2 MJ m-3)and high failure strain(?14.8%).Under different load levels,the conductivity of the fiber is maintained at about 85%.We showed that super-tough conductive fibers can be used in wearable materials,and can show rapid response to a variety of external stimuli(humidity,applied force,and external current).The fiber can have high-efficiency electrothermal performance and electromechanical sensing performance,and can be used in the application of next-generation wearable devices.(4)The method of pre-wet stretching and rapid drying is used to improve the multi-level orientation structure of fibers,and improve the combination of secondary bonds between fibers,and finally achieve the purpose of reducing the size of the pores between the fibers and increasing the strength of the material.The mechanical strength of the directional spinning is?972.23 MPa,and the Young's modulus is?84.14 GPa,which exceeds the known cellulose/CNT-based fiber,and the specific modulus is comparable to that of steel wire rope.By combining cyclic tensile tests and molecular dynamics simulations to explore the interface and structural relationships between carboxymethyl cellulose,dopamine and carbon nanotubes,it was verified that highly aligned structures can enhance the strength of the interface and avoid adjacent atoms.The dislocations,as well as the combination of non-bonded interaction and twisting between the molecules,ensure the uniform transfer of the load within the structure.It can exhibit good respiratory sensitivity and effective electrothermal imaging stability,which plays an important reference value for improving the tolerance of smart electronic materials. |
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