Dispersion Of Nanoparticles In Polymer Matrices With Well-designed Ligands As Dispersant/emulsifier/comonomer

One of the fundamental issues upon the preparation of nanocomposites is to find a practical method for nanoparticle dispersion and stabilization in polymer matrices of different polarities.AmphipHiles appear to play a decisive role in avoiding aggregation of nanoparticles.The structure of amphipHiles would affect the dispersion of nanoparticles in both aqueous solutions and polymer matrix.Therefore,designing amphipHiles for dispersing nanoparticles is the key of improving nanocomposites'performance.In this thesis,cationic ligand Vinylbenzyldimethyldodecylammonium chloride?VDAC?and anionic ligand Sodium monododecyl maleates?MAMS?were designed to serve as dispersant,emulsifier and comonomer in different stages of nanocomposites preparation.Commercial BaTiO₃,TiO₂,Ag and Al₂O₃ nanoparticles were incorporated and dispersed uniformly in PS and PMMA matrices by designed cationic/anionic ligand.Nuclear magnetic resonance?¹H-NMR?was used to demonstrate the synthesis of anionic/cationic ligand.Dynamic photoelastic scattering?DLS?was adopted to test the particle size of nanoparticles in water as well as the paticle size of emulsion polymerization microspheres.Transmission Electron Microscope?TEM?was used to characterize the dispersion of nanoparticles in polymer matrix.X-ray photoelectron spectroscopy?XPS?was applied to demonstrate the copolymerization of cationic/anionic ligand with St or MMA.Meanwhile,the mechanical performance and thermal performance of nanocomposite films were also discussed.As dispersants,the sizes of nanoparticles aggregates were reduced from thousands of nanometers to dozens of nanometers by cationic/anionic ligand.Then ligands served as emulsifiers to prepare polymer nanocomposites.At the end of emulsion polymerization,the ligands copolymerized with polymer matrices.At this stage,the sizes of nanoparticles in polymer matrices fell to several nanometers.After hot-pressing,nanoparticles maintained the stable dispersion state in polymer matrices.A facile and efficient approach was exhibited for preparing polymer nanocomposites with a large variety of chemically different nanoparticles in diversified polymer matrices.