Construction And Functional Application Of Macroscopic Two-Dimensional Janus Gold Nanoparticle Film

Two-dimensional(2D)gold nanoparticle film is prepared by the tight arrangement of its monodisperse nanoparticles in two-dimensional space.Different from one-dimensional monodisperse particles and three-dimensional bulk materials,2D monolayer films of gold nanoparticles show distinctive chem-physical propertie,greatly expanding the application fields and scopes of noble metal nanomaterials,and has become a research hotspot.However,the conventional 2D gold nanoparticle films usually possess symmetric structures and identical properties on both sides,which limit their applications in many fields.In view of the increased demand for multifunctional applications,the Janus materials have been reported.It is of great significance to construct the 2D Janus gold nanoparticle monolayer films with asymmetric properties and functions by changing the physical structures or chemical compositions of two sides.Based on the interface self-assembly and epitaxial growth of noble metal nanoparticles,the following three aspects are discussed in the thesis:1.The macroscopic two-dimensional gold nanoparticle film obtained by self-assembly at the water-oil interface was used as the seed,which was transferred to the surface of growth solution containing HAu Cl₄,ligand 4-MBA and ascorbic acid(AA).The 2D Janus gold nanoparticle monolayer film with different bifacial morphologies was obtained by asymmetric epitaxial growth at the air-liquid interface.The effects of the relative concentrations of 4-MBA and HAu Cl₄in the growth solution on the bottom surface of the Janus film were investigated,the shape of gold nanoparticles in the 2D film was changed to regulate the top surface of the Janus film,and the effects of different crystal surfaces of gold nanoparticles on the growth pattern were compared.We also studied the growth patterns and morphologies of Ag,Pt,Pd growth solutions using gold film as seed for epitaxial growth.The method to construct the 2D Janus gold nanoparticle film is simple,rapid and universal,which is of great significance for the construction of advanced plasmonic materials with new functions.2.The 2D Janus gold nanoparticle film has different bifacial morphologies,which exhibits asymmetric wetting properties,optical properties,and SERS effects.Given the 2D Janus film was obtained by asymmetric epitaxial growth at the air-liquid interface without the limitation of solid substrate,it can be easily transferred to a variety of substrates(such as silicon,quartz glass,PDMS).The 2D monolayer film of noble metal nanomaterials with unique properties can become the component of advanced materials and devices with great attraction and prospect,expanding the application fields and scope of gold nanoparticles.3.The 2D gold nanoparticle film was combined with PNIPAM hydrogel by copolymerization using thin and transparent PDMS as the transfer medium to prepare the Janus gold film-PNIPAM hydrogel.Combining the photothermal conversion properties of the gold film and the temperature-sensitive reversible phase transition of the PNIPAM hydrogel,the Janus gold film-PNIPAM hydrogel material has a rapid conversion of transparent/opaque in response to optical switch.We have studied the photoresponsiveness of the Janus material compounded by PNIPAM hydrogel and the2D film of gold nanoparticles with different sizes and morphologies,as well as the practical application in the field of smart windows,which will greatly expand the application prospect of noble metal nanomaterials in smart optical devices.In this thesis,the 2D Janus gold nanoparticle films were obtained by morphology tuning and copolymerization with otheir compositions.The free-standing 2D Janus gold nanoparticle monolayer film has bifacial adjustable morphologies and compositions,which can be transferred onto various substrates and exhibits asymmetric wetting properties,optical properties,and SERS effects because of the significant differences in morphologies at the two sides.The Janus gold film-PNIPAM hydrogel material has both the photothermal conversion property and the temperature-sensitive reversible phase transition property,which shows the excellent performance of fast reversible conversion of transparent/opaque in response to optical switch.It will have great value of application in the field of smart windows.