The Preparation And Modification Of Mesoporous Silica And Its Application In Polymer

In this thesis, mesoporous silica nanoparticles with different sizes, shape and pore ordering and colloidal mesoporous silica with different stability and morphology were synthesized by varying the surfactant template. The mesoporous silica nanoparticles was systematically characterized by small angle X ray diffraction(SAXRD), transmission electron microscopy(TEM), and nitrogen adsorption/desorption techniques and the colloidal mesoporous silica was characterized using TEM, dynamic light scattering instrument(DLS) and nitrogen adsorption/desorption techniques. The obtained mesoporous silica nanoparticles were further compounded with 2, 2- methylene bis(4, 6- ditertbutyl dimethoxy) sodium phosphate(NA-11), and then the compounded nucleating agent was added to isotactic polypropylene(i PP) to investigate their effect on crystallization behavior and properties of i PP. Mesoporous silica(PC16MS) containing N-cetyltrimethylammonium bromide(C TAB) was prepared by means of sol- gel then dried by spray drying method and added to i PP to investigate their effect on crystal ization behavior and properties of i PP.For preparation of mesoporous silica nanoparticles, the influence of the post-processing method(calcination and reflux), the amount of tetraethoxysilane(TEOS) as well as surfactants on mesoporous silica morphology structure was investigated. The result showed that mesoporous silica particles with stability skeleton structure could be obtained by calcination with surfactant could be removed completely. The mesoporous silica particles with better shape and pore ordering were prepared while the dosage of TEOS is 5 ml, with the particle size is less than 100 nm. With long chain alkyl(C14- C18) trimethyl ammonium bromide as surfactant, as the alkyl chain length increased, mesoporous silica particles morphology varied from sphere to rod. With long chain alkyl(C16) trimethyl ammonium bromide as surfactant, the nano-sized spherical mesoporous silica particles possess order hexagonally channel. With long chain alkyl(C14- C18) methyl di-hydroxyethyl ammonium bromide as surfactant, with the increase of alkyl chain length, mesoporous silica particles varied from rod to spherical, and the pore ordering were lower than that with the trimethyl quaternary ammonium salt as surfactants.For the synthesis of colloidal mesoporous silica, the effect of two series of long chain alkyl quaternary ammonium salt, the long chain alkyl(C14- C18) trimethyl quaternary ammonium salt and long chain alkyl(C14- C18) methyl di- hydroxyethyl quaternary ammonium salt as surfactants respectively on colloid stability and morphology structure of colloid particle was investigated. The research showed that for the two series of surfactant, the stability of the colloid reduced and the size of colloid particle increased with the increasing of the length of the alkyl chain. With the long chain alkyl(C14) quaternary ammonium salt as the surfactant template, the stability of the colloid was the best. With the long chain alkyl(C18) quaternary ammonium salt as the surfactant template, colloidal particles aggregated in a short time. The colloidal particles with raspberry morphology or worm- like pore structure can be obtained with the chain length of C14 and C16.For the application of mesoporous silica in i PP, the effect of mesoporous silica nanoparticles, mesoporous silica nanoparticles/N A- 11 and colloidal mesoporous silica containing the surfactant after spray drying on structure and properties of i PP was investigated. The research showed that mesoporous silica nanoparticle and hybrid nucleating agent can improve the crystallization, transparency properties and other physical properties effectively and reduce the haze of i PP. With the addition of 3‰ spherical mesoporous silica nanoparticles/NA- 11, the crystallinity of nucleated PP reached 44.72%, the haze decreased to 20.3% and the transparency increased by 67.8%, compared to pristine i PP. The flexural strength increased by 26.8% and flexural modulus increased by 14.7%, and the vicat softening temperature increased by 6.6℃.The initially obtained nanoparticles were recomposed to monodispersed circular aggregates with size about 20 μm by spray drying, and the mesoporous silica aggregates can be broke easily then the partic les dispersed in nanoscale in i PP. Organic mesoporous silica particles can significantly accelerate the primary nucleation process, minimize the spherulite radius, shorten the time of crystallization increase the crystallization temperature and crystallinity of i PP, which suggested PC16 MS can be used as an effective nucleating agent for i PP.