Preparation,Properties And Applications Of Ultralong Hydroxyapatite Nanowire-based Biomimetic Materials

After billions of years of evolution,many natural materials with unique functions and excellent properties have been created by nature.These functional or structural materials in nature supply a rich source of design inspiration and guidance for our research,and preparation of biomimetic materials with specific functions or structures has become a research focus in the field of Materials Science.As the building block for constructing biomimetic materials,biocompatible and bioactive hydroxyapatite material is one of ideal choice.However,the reported hydroxyapatite-based biomimetic materials are usually made from hydroxyapatite materials with particles,rods or flakes morphologies.Because of the high brittleness of these hydroxyapatite materials,the resulting biomimetic materials always have poor properties.In this dissertation,by means of compositing,doping or modifying,a series of ultralong hydroxyapatite nanowire-based biomimetic functional and structural materials have been developed,and the properties and promising applications of these biomimetic materials in multidisciplinary fields have been studied.The main points of this dissertation are as follows:1.The magnetic and superhydrophobic biomimetic paperA biomimetic paper with magnetic and superhydrophobic properties has been constructed.For the preparation of this paper,ultralong hydroxyapatite nanowires are synthesized by the calcium oleate precursor solvothermal method and modified with magnetic Fe₃O₄ nanoparticles and coated with polydimethylsiloxane.This biomimetic paper has a porous structure,high flexibility,magnetic responsiveness,superhydrophobicity,high-temperature resistance and nonflammability.This biomimetic paper can be used as the oil/water separation filter paper and magnetically driven oil separation device.When it is used as the oil/water separation filter paper,this biomimetic paper exhibits a high separation selectivity?99.6%?and high permeation flux(2835.9 L m^-2 h^-1).When this biomimetic paper is used as the magnetically driven oil separation device,it shows a high separation efficiency??99.2%?for many kinds of oils.Therefore,this biomimetic paper is expected to be used in the areas of oily wastewater treatment and environmental restoration.2.The luminescent and superhydrophobic biomimetic paperThe rare earth ion-doped ultralong hydroxyapatite nanowires are prepared by the calcium oleate precursor solvothermal method,and the biomimetic paper with luminescent and superhydrophobic properties is made from oleic acid-modified and rare earth ion-doped ultralong hydroxyapatite nanowires.The effects of the sort and the concentration of rare earth ions on the morphologies and luminescent properties of the product are investigated.Taking advantages of its multiple functions such as photoluminescence,superhydrophobicity,high-temperature resistance,and nonflammability,the as-prepared luminescent and superhydrophobic biomimetic paper is exploited for various applications such as multimode high-security anticounterfeiting materials,forgery-proof labels,high-security packaging and documents.3.The self-propelled superhydrophobic biomimetic paper and double-mode self-propelled superhydrophobic biomimetic paperInspired by the water strider,a self-propelled superhydrophobic biomimetic paper has been developed.Ultralong hydroxyapatite nanowires are synthesized by the calcium oleate precursor solvothermal method and decorated with polydopamine and oleylamine,and then used as the building materials for constructing the self-propelled superhydrophobic biomimetic paper via the facile vacuum filtration process.The photothermal function of the self-propelled superhydrophobic biomimetic paper enables it to convert light power into heat power,that then triggers the Marangoni effect to realize self-propelled motion.The superhydrophobicity of the self-propelled superhydrophobic biomimetic paper not only makes the paper spontaneously float on the water surface,but also introduces a bubble layer between the paper and the water surface which can effectively reduce the fluid drag.The maximum moving speed and response time of the self-propelled superhydrophobic biomimetic paper can reach22.14±4.89 mm/s and 0.10±0.03 s,respectively.The as-prepared self-propelled superhydrophobic biomimetic paper is promising for applications in the fields of micro-robots,biomedicine,and environmental remediation,etc.Based on the work of the self-propelled superhydrophobic biomimetic paper,a double-mode self-propelled superhydrophobic biomimetic paper has been developed.Ultralong hydroxyapatite nanowires are used as the platform for loading Ti₂O₃particles and coating with polydimethylsiloxane to construct this paper.The as-prepared double-mode self-propelled superhydrophobic biomimetic paper owns excellent high-temperature resistance,nonflammability,photothermal conversion and superhydrophobicity,which enable it to realize double-mode self-propulsion.In normal conditions,the self-propelled motion is achieved by triggering the Marangoni effect.In the case of the surfactant aqueous solution,the propulsion mode of the as-prepared biomimetic double-mode self-propelled paper is switched into vapor-enabled mode by adjusting the light power density,which enables this paper to move on the surface of the surfactant aqueous solution.The dual self-propulsion mode makes the double-mode self-propelled biomimetic paper own wide applicability.4.The high-performance hydroxyapatite nanowire-based composite fibers with biomimetic structuresThe quasi-long-range orderly liquid-crystalline ultralong hydroxyapatite nanowires and sodium polyacrylate are used to fabricate the composite fibers by a scalable and eco-friendly wet-spinning approach.The as-prepared composite fibers have unique“brick-and-mortar”layered structure and highly ordered structure,which endows the fibers with excellent mechanical properties.The maximum tensile strength and Young's modulus of the as-prepared composite fibers can reach 203.58±45.38 MPa and 24.56±5.35 GPa,respectively.In addition,the biomimetic composite fibers also show good flexibility and processibility,so it can be prepared into various shapes.The biomimetic composite fibers with magnetic or fluorescent function can be prepared by introducing the magnetic or fluorescent component.Due to its excellent performance,the as-prepared biomimetic composite fibers are expected to be used in tissue engineering,flexible intelligent fabric,and functional wearable devices.In this dissertation,a series of biomimetic functional and structural materials are prepared by using flexible ultralong hydroxyapatite nanowires as building units.The multi-functionalization of these biomimetic materials is realized by means of compositing,doping or modifying.Meanwhile,the flexible inorganic skeleton endows these biomimetic materials with excellent flexibility and high temperature resistance and non-combustibility.The results indicate that the ultralong hydroxyapatite nanowire is an ideal choice for the construction of high-performance biomimetic materials.