In Situ Measurement On The Size And Surface Group Of The Nanoparticle In Suspension

In this thesis,the morphology of nanoparticles in solution dispersion and in situ measurement of the surface state were studied by employing NMR and UV-Visible spectroscopy.The research contains two parts:In this thesis,we firstly employed the low field NMR(LF-NMR)to perform in-situ measurements on the wet specific surface area of the silica nanoparticles.According to the different types of surface functional groups of different silica nanoparticles,we could clarify the number of bound water molecules on the surface of the silica nanoparticles and the number of corresponding surface functional groups.In this paper,the modified silica nanoparticles were used for experiments and analysis.The number of amino groups per unit area of the amino-modified silica nanoparticles is 3.7 / nm~2.The number of carboxyl groups per unit area of the carboxylated silica nanoparticles part is 2.3 / nm~2;The number of hydroxyl groups per unit area of the hydroxyl-modified silica nanoparticles is 4 / nm~2.The outcomings are consistent with the previous reported data,which proved that it can be used for in situ qualitative and quantitative analysis of the physical and chemical characteristics of nanoparticles surface.Another aspect of this thesis is the utilization of UV-Visible spectroscopy(UV-Vis)for the real-time detection and recording the absorbance of nano-particles in solution,and then to calculate the corresponding turbidity.Based on the Rayleigh scattering approximation theory(RGDA),the turbidity can be used to calculate the distribution of nanoparticle particle’s size,and the thickness of the cladding layer can be determined for particles coated with heterogeneous materials.Based on the principle of light scattering,this method is only applicable to the material system of zero absorption in the ultraviolet and visible spectral range,in which case the scattering of light with the particles is the only cause of turbidity(absorbance).This technique enabled us to successfully investigate the size of the nanoparticles together with its coating thickness according to the turbidity,in addition with exhibiting comparable high accuracy,sensitivity and convenience to the dynamic light scattering measurements.The experimental data was compared between two techniques,with characterizing two different polystyrene microspheres coated with bovine serum albumin(BSA).The thickness of the coating obtained by turbidity were 4.5nm and 3.8nm respectively,which were in agreement with those obtained by dynamic light Scattering(DLS)measurements.And in the characterization of the silica nanoparticles,measurements were carried out with changing the different dispersion time,with the increase of the dispersion time,the degree of dispersion of silica nanoparticles become better,when the dispersion time exceed 15 min,the absorbance is no longer obvious.The results show that the dispersion of silica nanoparticles is generally stable.The above experimental results are consistent with the data obtained by other conventional methods,which certified the reliability of our technique.