Preparation And Characterization Of Non-Spherical Polymer Based Hollow Nanostructures With Tailorable Functionalities

Hollow nanostructure refers to a kind of material with nanoscale size and containing inner voids.As one of the family of functional materials,hollow nanostructure integrating the functional shells with interior architecture provide low density,large surface area and shorten the diffusion path of both mass and charge.Due to their unique physical and chemical properties,hollow nanostructures have drawn tremendous amount of interests,and shown promising applications in catalyst,biomedicine,photoelectricity,environmentology and so on.In the past decade,considerable methods have been designed for hollow nanostructures preparation,such as layer-by-layer,microemulsion method,self-template,Oswald ripening,etc.Despite wide applicability of these strategies,there are still difficulties for anisotropic hollow nanostructures preparation since the shortage of the available non-spherical template materials.Moreover,most of the existed approaches are developed for inorganic nanostructures synthesis.Expanding these ideas to construct polymer based hollow nanostructures still remains a challenge.In this work,a novel method is exploited for synthesis of non-spherical polymer based hollow nanostructures.The method is based on ‘chelation competition induced polymerization' mechanism,and the polymerization process is accompanied with the disassembly of template materials.Such train of thought shows novelty,mildness,and ingenuity,which may provide a platform for construction of series of polymer based hollow nanostructures.In chapter 2,we firstly demonstrate the ‘chelation competition induced polymerization'?CCIP?method by using polydopamine?PDA?nanocontainers as examples.The PDA nanocontainers are prepared by using metal-organic frameworks,ZIF-8,as template materials and dopamine?DA?as monomer.The synthetic mechanism of the CCIP method has been studied in detail and further proved by theoretical calculation of the binding energy between metal cations and ligands.The formation process of the hollow nanostructures has been observed by monitoring the nanostructure changes at different reaction time.The structure of the obtained PDA nanocontainers can be precisely controlled by modulating the reaction conditions.Series of PDA nanocontainers with different morphologies and chelated metal ions are prepared by changing the template materials.Moreover,different polymer hollow nanostructures can be obtained by expanding DA to other monomers.The biomedical performance of the as prepared PDA nanocontainers have been investigated,which demonstrate that the polymer nanocontainers obtained by our CCIP method show good biocompatibility,high drug loading efficiency and the excellent photothermal properties,offering possibility in biomedical applications such as multifunctional anti-cancer platform.In chapter 3,functional nanoparticles,gold nanorods?AuNRs?,has been successfully introduced into the system to realize the functionalization of PDA nanocontainers.After modified with polyvinylpyrrolidone?PVP?,AuNRs can be easily encapsulated into ZIF-8 templates,showing no effect on the formation of ZIF-8and PDA nanocontainers.The obtained nanostructures?AuNRs@PDA NCTs?shows good biocompatibility,excellent photothermal property,high drug loading efficiency together with controllable release performance.Both cell and animal experiments indicate the excellent chemo-thermo performance of AuNRs@PDA NCTs loaded with drug?DOX,typical anti-cancer drug?,making it a promising candidate for cancer eradication.Moreover,due to the introduction of AuNRs,the AuNRs@PDA NCTs also show good performance in CT imaging.In chapter 4,we replace the functional nanoparticles from AuNRs to Fe₃O₄ NPs and further carbonize the as-prepared Fe₃O₄/PDA nanocages to dodecahedral carbon nanocages with Fe₃O₄ NPs incorporated?Fe₃O₄/C NCs?.The obtained Fe₃O₄/C NCs show high loading efficiency of Fe₃O₄ NPs,N-doped and controllable structure.Due to the electrochemical properties of Fe₃O₄ NPs and the inner void of the nanocages,Fe₃O₄/C NCs can be used as anode materials for Lithium ion battery?LIBs?.The results indicate good cycling performance and stability of Fe₃O₄/C NCs,and the hollow structure can effectively reduce the volume tension of Fe₃O₄ NPs during charge-discharge process.After carbonizing at high temperature?ca.900 oC?,the obtained Fe₃O₄/C NCs can be further purified and display a very high specific capacity?ca.1000 mAh g-1?.In addition,other polymer based hollow nanostructure prepared through our CCIP method can also be carbonized and applied as anode materials for LIBs,showing good electrochemical performance.In conclusion,we have exploited a novel method,which is based on ‘chelation competition induced polymerization'?CCIP?mechanism,for construction of non-spherical polymer based hollow nanostructures.Such method not only provides a platform for fundamental research,but also offer possibilities for practical applications of polymer hollow nanostructures with tailorable functionalities.By following the train of thought that combines the theory study with practical application,we have successfully prepared and characterized non-spherical polymer based hollow nanostructures with tailorable functionalities.The novel strategy,clear synthetic mechanism and excellent performance of the polymer based hollow nanostructures are achieved in the present paper.