The Design Synthesis And Application Of Monomolecular Polymer Nanovesicles

Owing to the hollow structure,the nano-vesicles have large specific surface area and the density is far lower than that of nanoparticles with composition and size.Therefore,nano-vesicles have attracted extensive attentions in the fields of biological imaging,drug carrier and bionic micro-nano container.Among various types of nano-vesicles,single-molecule nano-vesicles have the advantages of simple preparation process,large yield,good structure stability and not susceptible to p H value and temperature.In this thesis,a general method for the preparation of single molecule nano-vesicles with different shells has been developed.Firstly,a multi-arm star-shaped polycaprolactone?PCL?,a typical degradable polymer,was synthesized as the core,and then the second polymer block was grown as the shell layer by controllable free radical polymerization.Finally,the shell layer was cross-linked and the PCL core was degraded to get the single-molecule nano-vesicle.Here,three kinds of single molecule nano-vesicles with different shells were prepared and their potential applications were also studied.The specific research work is as follows:?1?Preparation of PS single molecule nanovesicles and their application as universal nanoreactors for the synthesis of nanocrystals.A?-cyclodextrin-based multi-arm star block polymer PCL-b-P?S-Cl?was prepared by ROP and PET-RAFT reaction,and the Cl group was nucleophilically substituted with Na N₃ to obtain a star block polymer PCL–b-P?S-N₃?.The core-shell polymer was obtained by cross-linking P?S-N₃?under UV light at 254 nm.Single-molecule nano-vesicles with PS shell were obtained by degradation of core PCL with acid.Ag,Au,Cu₂O and Fe₃O₄ nanocrystals were synthesized by using single molecule nano-vesicles as general nanoreactosr.By controlling the molecular weight of the core PCL,the size of the hollow structure of the single-molecule nano-vesicle can be regulated,and the size of the nanocomposite can be controlled.?2?Preparation of SiO₂ single-molecule nanovesicles and their application as nanoreactors for the synthesize Ag@SiO₂ core-shell nanoparticlesMulti-arm star-shaped block polymer PCL-b-PTMSPMA was synthesized through ATRP with star-shaped PCL as the firs block.Organic silica core-shell polymer was then obtained by hydrolysis of PTMSPMA block under alkaline conditions.SiO₂shell single-molecule nano-vesicles were obtained by acid degradation of core PCL.Ag@SiO₂ core-shell nanoparticles were synthesized by using single molecule nanometer vesicles as nanoreactor.The results show that the thickness of organic silica core-shell polymer shell can be affected by the degree of hydrolysis cross-linking.Moreover,,the hollow size of the SiO₂ single-molecule nano-vesicle can be regulated by controlling the molecular weight of the core PCL,and the size of the Ag particles in the core-shell structure of Ag@SiO₂ can thus be controlled.?3?Preparation of light-responsive single molecular nano-vesicles and their applications in dye load and release.With the star-shaped PCL as the core,the photoresponsive monomer MAMC was introduced and the multi-arm star-shaped block polymer PCL-b-PMAMC was synthesized by ATRP polymerization.The PMAMC block can be cross-linked under the irradiation of 365 nm ultraviolet light and lead to the formation of PMAMC single molecular nano-vesicles after the acid degradation of PCL.Moreover,the cross-linking of PMAMC shell can be unlocked with the irradiation of 254 nm ultraviolet light.Therefore,we studied the application of light-responsive nano-vesicles as the carrier of dye.By comparing the dye release curves in the dark and 254 nm ultraviolet light after the dye loading,we demonstrate the potential application of the light-responsive nano-vesicles in the field of drug loading.