Nano Modification Of Polymer Based Micro Nano Multilayer Optical Thin Films

Polymer based nanocomposites have their respective advantages and synergies of nanoparticles and polymers,and are widely used in aerospace,medical instruments,electronic instruments and intelligent automation industries.In this paper,the nanometer modification method is used to improve the dispersion of nanoparticles in the polymer matrix and improve the comprehensive properties of the polymer based nanocomposites.The emphasis is on the optical properties of the nanocomposites,and the results obtained are as follows:(1)Molecular dynamics simulations were carried out to investigate the dispersion of fullerene nanoparticles in polyethylene films.The influence of the spatial confinement,pressing,deformation rate on the dispersion of nanoparticles in the polyethylene film was analyzed.The obtained results indicate that the spatial confinement of the film hinders the dispersion of the C60 nanoparticles.With an axial pressing on the film,the compression on the nanoparticle aggregate is able to enhance the dispersion of nanoparticles in the film.With a fixed deformation amount in the z direction,reducing the deformation rate would give rise to better nanoparticle dispersion in the film.When the deformation slows to an adequately small rate,the dispersion of the fullerene nanoparticles would approach to that in the bulk material of polyethylene.(2)By the molecular dynamics method,the modified nano-SiO2/PMMA film system is simulated,to analyze the influence of content and the particle size of modified nano SiO2 particles on the mechanical properties and interface of the thin film system.Taking the actual effect of light transmittance into account,we set the concentration of nanoparticles in the lower range(2%-11%),and due to the limitation of molecular modeling,the particle size of nanoparticles,is set to lnm,2nm,3nm.The results show that the low concentration level changes of the modified nano-SiO2 particles has a small impact on the mechanical properties and the interface of the film.Under the same concentration,with the size of nanoparticles increasing,there is greater impact on mechanical properties and interfacial:the maximum yield strength of thin films decreases,the elongation at break and interfacial bonding strength increase,and when the size of the nanoparticles is 3nm,the interfacial bonding is greatly enhanced.(3)The modified nano silica/polymethyl methacrylate composite was prepared.First,the modified materials were analyzed by Fourier transform infrared spectroscopy,and the principle of internal modification was explored.It was found that the coupling agents did not react with polymers,but only on the surface of nanoparticles,the hydroxyl groups were encapsulated,and then combined with hydroxyl groups on the surface of polymers.With the drawing machine,we explore the effect of nanoparticles content on the mechanical properties,with the increase of nanoparticles concentration,mechanical properties of composite material along the extrusion direction and perpendicular to the extrusion direction increased first and then decreased.But the elongation along the extrusion direction and perpendicular to the extrusion direction gradually decreased,and the elongation along the extrusion direction is better than perpendicular to the extrusion,because the direction of the molecular chain orientation along the extrusion direction is better.The dispersion of internal nanoparticles can be observed by electron microscope.It can be seen that the dispersion of nanoparticles in the polymer matrix is better and even after stacking.With the increase of nanoparticle content,the agglomeration of nanoparticles is more and more serious.The double beam UV spectrophotometer,infrared reflectivity measurements of composite materials and the transmittance of visible light,it can be seen that with the increase of the content of nanoparticles,reflectance and transmittance increased first and then decreased,when the content of nanoparticles was 3.5%,the optimum optical properties of composite material.At the same time,the experimental results also verify the above two chapters conclusions of molecular dynamics simulation.(4)The composite of modified nano titanium dioxide/polymethyl methacrylate was prepared.The content of modified nano titanium dioxide is set to 0.2%,0.5%,1%,2%,by double beam UV spectrophotometer,UV test film absorption and visible light transmittance,as can be seen,Ti02 can greatly improve the UV absorption rate of composite material,with the increase of Ti02 content,purple the absorption rate is also increased,but the visible light transmittance decreases obviously,considering the content of Ti02 is 0.5%,the optical properties of composite materials,at the same time with the increase of Ti02 content,nanoparticles to crosslinking agent in the polymer,the heat resistance of the composites reinforced.