Synthesis Of Multi-functional Nanomaterials Based On Hyperbranched Polymer Vesicles As Templates

Template-directed synthesis is a classical approach to defined nanostructured materials.The basic concept is to utilize templates to restrict the guest species and direct their growth toward the controlled construction of final product.Vesicles have been considered as promising templates and attracted vast interest during the past decades.However,most of vesicle templates used in the reported literature are based on surfactant vesicles,lipid vesicles,and block copolymer vesicles.Therefore,how to widen the species of vesicle templates and develop multi-functional nanomatrials with the same template in a facile and general way,has become the advanced research hotspots.Hyperbranched polymer vesicles,named as branched-polymersomes?BPs?,have displayed interesting properties such as a large population of terminal functional groups,better stabiligy,special membrane structures.Up to now,most of the applications of BPs are focused on drug delivery,mimic of cells and encapsulation.However,there were few reports about the research on the templating applications of BPs.In this dissertation,using BPs as soft templates provids a novel and powerful strategy to fabricate defined nanostructured materials.This dissertation can be divided into four major sections,and the main research contents and achievements are summarized as follows:1.Fabrication of hybrid vesicles with surface fully covered by noble metal nanoparticlesThis chapter studies on the facile preparation of hybrid polymer vesicles with surface fully covered of metal nanoparticles by using a novel hyperbranched polymer vesicle as templates.Amphiphilic hyperbranched multiarm copolymer HBPO-star-PEO?HSP?was first synthsized by cationic ring-opening polymerization.Then,through the end group modification,Dimethyl Carbamoyl groups?DC?were grafted on HSPs.The vesicle templates were prepared through the aqueous self-assembly of a hyperbranched multiarm copolymers with many Dimethyl Carbamoyl groups on the surface,which can electrostatically complexed or coordinated with metal ions like AuCl₄^-,PtCl₆^2-and Ag⁺ions.Subsequently,the vesicles coated with metal ions can be in-situ reduced into metal nanoparticles,through which a series of surface-engineered vesicles?Au@vesicles,Ag@vesicles,Pt@vesicles?with an advantage of fully covered metal nanoparticles on the surface could be readily prepared.The morphologies,structures,loading of particles and formation mechanism of the as-prepared hybrid vesicles were carefully characterized,and the obtained hybrid vesicles also showed great potentials in catalysis,biological simulation and surface-enhanced Raman scattering?SERS?applications.2.Polymer vesicle sensor for visual and sensitive detection of SO₂This chapter studies on polymer vesicle sensor for the visual detection of SO₂ and Ultraviolet-responsive vesicle sensor by surface-engineering of pH-responsive BPs.Tertiary amine alcohol?TAA?groups were grafted onto HSP to get objective product?HSP-TAA?,which can self-assemble into pH-responsive vesicles with enriched TAA groups on the surface.With the increase of pH,aggregation-induced fusions among vesicles were observed.By proton exchange,the TAA-coated vesicles were capable of immobilizing Cresol red?CR?on the surface to get CR@vesicles.The BPs exhibit an evident enrichment effect of the TAA groups and CRs,which significantly facilitates the SO₂ recognition process and leads to a low detection limit of 25 nM.Meanwhile,through electrostatic attraction,TiO₂@vesicles were obtained which can be triggered to rupture by ultraviolet.3.Monodisperse silicon nanospheres by vesicle bilayer templating:fabrication and high-performance anodes in Li-ion batteriesHydrophobic silicon source of TEOS were solubilized in the hydrophobic domains of the vesicle bilayers.The initiation of intra-vesicular sol-gel reaction was carried out by adding ammonium hydroxide solution.Monodisperse silicon nanospheres were synthesized through scalable magnesiothermic reduction of silica nanospheres which were obtained by sol-gel reaction inside polymer vesicle bilayers.TEM images of intermediates at different stages were collected to provide direct evidences of mechanism.Such Si nanospheres?35 nm?as an anode material exhibited high,reversible capacities(>1100mAhg^-1 after 100 charge-discharge cycles at 1.0 Ag^-1).4.Synthesis of mesoporous SiO₂,core-shell nanoparticles and ultra-fine PS,PMMA colloidal particles by vesicle bilayer templatingBy using the bilayers of BPs as templates,a series of nanomaterials ranging from mesoporous SiO₂,core-shell nanoparticles and ultra-fine PS,PMMA colloidal particles were prepared by altering the hydrophobic precursors.?1?Hydrophobic silicon source of TEOS and C₁₈TES were solubilized in the hydrophobic domains of the vesicle bilayers.Massive uniform C₁₈-SiO₂ particles were obtained doping with long carbon chains.After calcination at 800?,long carbon chains were removed leaving mesoporous SiO₂.?2?Core-shell structure of CdSe-SiO₂ were synthesized by using CdSe quantum dots as nucleation seeds and TEOS as hydrophobic silicon source under the restriction of the vesicle bilayers.?3?Ultra-fine PS,PMMA colloidal particles were prepared by the direct photopolymerization of styrene or methyl methacrylate inside the bilayers of BPs.This technique has been proved to be a general method for the preparation of uniform polymeric or hybrid particles with small size,which should be extended to prepare other uniform nanoparticles on a large scale.