Polytetrafluorine-like Nanocrystals Film By Atmospheric Pressure Oriented Plasma Polymerize And Its Properties

One dimensional (1D) nanomaterials have been attracting much attention recently for their tremendous potential applications in nanoscience and nanotechnology. The 1D nanomaterials in terms of nanotube, nanowire and nanobelts are widely employed in nannodevices, photoelectronic devices and sensors for their specific physical and chemical characteristics. It is accepted that the preparation and characterization of nanomaterials both are most important issues. In nanomaterials preparation, plasma technologies, especially nonthermal atmospheric-pressure plasmas, are considered to be a feasible and effective method with low-cost for forming crystal nanostructures, in which, the nanostructures are formed with process of assembling or etching by electrons, atoms, ions, excited molecules generated in plasma.In this thesis, a novel method of "atmospheric oriented plasma polymerizations" is developed for forming single crystalline fluorocarbon polymer nanotubes and/or nanorods, in which, an asymmetrical electrical field with gradient in plasma is used for generating and polarizing the reactive species. The results are listed briefly as following:PartⅠ: Characterization of plasmas dischargeThe experimental set-up applied in our study is a dielectric-barrier cylindrical reactor, the discharge characteristics in which are investigated with electrical measurements and numerical simulation. The measured waveforms of applied voltage and discharge current suggest that the discharge is a typical dielectric-barrier discharge (DBD) and is filled with filaments. Further studies on discharge characteristics are carried out with a numerical simulation of particle in cell (PIC). The dynamics and evolution of microdischarge are demonstrated by spatial-temporal distribution of electron density, ion density, surface charge density and electric field. It shows that these charged particles in discharge are all accumulated in the regime above dielectric layer surface at anode, which suggests an asymmetrical electric field with gradient around anode.PartⅡ: Fabrication and manipulation of morphology in PTFE-like polymer nanocrystals filmsWith atmospheric DBDs, the PTFE-like polymer nanocrystals films can be obtained within a short period of time ranging from a few seconds to several minutes, in which, different morphology nanocrystals in terms of nanorods, nanoparticles and nanotubes are all found by SEM. Furthermore, it is confirmed that these nanocrystals are in phase of single-crystaline by TEM and XRD results. Additionally, the dependence of nanocrystalline morphology and crystallinity on discharge parameters of discharge time duration, flow ratio of monomer to carrier gas and discharge dissipated power were investigated. The results demonstrate that the physical morphology and structures could be manipulated with the discharge conditions, especially for the oriented plasma polymerization. It suggests that this novel polymerization method offers a rapid and effective way for fabricating polymeric nanocrystallines.For better understanding of underpinning film growth mechanism, the procedure of nanocrystalline film synthesis is discussed, correlated to discharge characteristics. It suggests that the asymmetrical gradient electrical field plays an important role on growth of -one dimensional nanocrystals oriented plasma polymerizations, based on which, the growth model named "one dimensional activated growth model limited by gradient electrical field" is proposed for explanation of film growth mechanism.PartⅢ: Hydrophobic properties and thermal properties of nanocrystals filmsThe result of PLM and TGA indicates that the title compound keeps stable up to temperature of 350°C. The contact angle of the water and 1-bromonaphthalene on coated cotton fabric was found to be 133°and 124°, separately. The surface morphology of the coating was examined through SEM. It was found that cotton fabric surface was tightly adhered to a thin film packed by nano-particles with diameter from 10 nm to 200 nm. This process showed potential applications in continuous coating of textiles with functional nano-particulate polymers, without changing their performance of softness.