Preparation Of Polymer/silica Nanocomposites By Soap-free Emulsion Polymerization

Polymer/inorganic nanocomposites combine the excellent properties of polymer and inorganic particles.The synergistic effect of the two can improve the mechanical and processing properties and thermal stability of the materials.The introduction of functional inorganic particles can also endow the materials with new functions such as catalysis,scratch resistance,transparency and optical properties,thus making polymer/inorganic nanocomposites useful for high-performance coatings,biomedicine,catalysis and textiles.Silica nanoparticle is easy to agglomerate,and it is difficult to be dispersed in polymer materials.Soap-free emulsion polymerization not only improves the dispersion of silica nanoparticles,but also directly forms a film for coatings.In this study,polydopamine was used to modify the surface of inorganic nanoparticles,and the modified inorganic nanoparticles and different monomers were subjected to soap-free emulsion polymerization to obtain polymer/inorganic nanocomposites.The factors affacting the preparation process of polymer/inorganic nanocomposites and the properties of the obtained nanocomposites were investigated.The main research contents and conclusions are as follows:1.Surface modification of inorganic nanoparticles through the self-polymerization of dopamine.TEM,DLS,Zeta potential and other testing methods were used to characterize the structure,morphology,stability and dispersibility of surface-modified inorganic nanoparticles.2.Polystyrene/silica?PS/Si O₂?nanocomposites were prepared by soap-free emulsion polymerization using polydopamine modified silica nanoparticles.We investigated the effects of initiator and initial concentration of modified silica on the colloidal stability and structural morphology of PS/Si O₂ nanocomposites.The nanocomposites were characterized by FTIR,XPS,SEM and TEM.The redox initiator APS/TMEDA was confirmed to be able to prepare PS/Si O₂nanocomposites with polystyrene as core and nano-silica as shell.Changing the initial concentration of silica sol can effectively control the structural morphology and colloidal stability of PS/Si O₂ nanocomposites and P?S-BA?/Si O₂ nanocomposites.3.We further investigated the factors affecting the preparation of poly?methyl methacrylate?/silica?PMMA/Si O₂?nanocomposites by soap-free emulsion polymerization.The amount of nano-silica coated polymethyl methacrylate increases with the increase of the initial concentration of the modified silica sol.Changing p H value will affect the charge density on the surface of latex particles and nano-silica and further affect the structural morphology and colloidal stability of PMMA/Si O₂.In addition,the addition of comonomer BA with a low glass transition temperature favors the film formation of copolymer/silica nanocomposite,broadening the further application and development of composite materials.