Study On Uniformity Of Nanoparticles Caused By Nanoprotrusion

With the extraordinary physical and chemical properties,nanomaterials have received extensive concentration from researchers and businesses for many years.Nanoparticle films as a nanomaterial has also been a research hotspot,which are key building blocks for photovoltaics,chemical/biological sensors,portable/wearable devices,magnetic devices,and catalysis.For these applications,high size and shape uniformities of nanoparticles play a decisive role in the performance of nanodevices.For example,noble metal nanoparticle films are commonly used as surface-enhanced Raman substrates for detecting the ultra-low concentrations of biological and medical molecules.The shape and size uniformities of nanoparticles will seriously affect the stability and detection limits of Raman signals.Another important application of nanoparticle film is magnetic devices,which are widely used in data storage and biomedical fields.For this application,the magnetic properties are mostly determined by the size and shape of nanoparticles via affecting magnetic domains and interactions.It can be seen that the uniformities of the size and shape of the nanoparticles play an irreplaceable role in the nanodevice.Magnetron sputtering is a common method for preparing nanoparticle films which was known as its advantages of being fast and efficient.However,it is difficult to control the uniformities of the size and shape of the nanoparticles,which makes the method difficult to be widely spread in various application fields.In this paper,we propose a strategy that can solve the above problems.The research work of this thesis is mainly from the following aspects:(1)Using a plasma etching technique to form a uniform size nanoscale protrusion on polymer substrates by chemical bond cleavage,recombination,and redeposition.And the Ag nanoparticles are superimposed on the PET substrate rich in nanoprotrusion by magnetron sputtering technology.Compared with the conventional sputter coating method,the Ag particles sputtered on nnoprotrusion enriched substrate with spherical shape and uniform size distribution.The mechanism of the uniform size and shape generation was analyzed by using surface plasmon spectroscopy and nucleation growth mechanism.(2)Universality is one of the criteria for measuring whether a preparation method isexcellent.In this work,we used gold(Au)sputtering on a nanoprotrusion enriched polycarbonate(PC)substrate and indium tin oxide(ITO)sputtering on the nanoprotrusion enriched polyethylene terephthalate,respectively.Metals and oxides with completely different properties,but the morphology of the Au and ITO nanoparticle films prepared by this method exhibits an unprecedented similarity,that is,the nanoparticles are spherical and with a relatively uniform size.The above experiments fully demonstrate that the preparation method of the nanoparticle film is universal.(3)Au nanoparticles are prepared on a nanoprotrusion enriched PC substrate with different sputtering rates,while ensuring the thickness of the nanoparticle films.It was found that the morphology of the Au nanoparticles was not affected by the sputtering rate,and the obtained nanoparticles were spherical and uniform in size.The mothed changes the phenomenon that the sputtering rate in the conventional sputter coating method seriously affects the morphology of the nanoparticle film.In summary,this paper has carried out a series of research work on the preparation of nanoparticles with uniform shape and size.The strategy comprises the steps of: forming a nanoprotrusion on a polymer substrate by using a plasma etching technique,depositing the nanoparticles on the nanoprotrusion enriched substrate to obtain a nanoparticle film with uniform shape and size,proving the universality of the strategy and its high tolerance to sputtering rate by using experiments.This study has great reference value for understanding the nucleation and growth mechanism of nanoparticles,preparing nanoparticles with uniform size and shape,and improving the efficiency of preparing nanoparticle films with specific shapes and sizes.