Investigations Of Structure And Properties In Silica Nanoparticles Enhanced Poly (Acrylate) Copolymer

Polyacrylate copolymer were widely applied in adhesives,paint,cosmetics and other fields because of the advantages of high quality,inexpensive,high gloss and easy to film.However,there are some deficiencies in hardness,solvent resistance and scratch resistance,which limit the application in industry.Therefore,it needs to be modified to meet the needs of more application.It has been confirmed the presence of silica particles in polymer materials is beneficial to improve the properties of the final productions,such as thermal stability,mechanical properties,transmittance and fire-resistant properties.In this paper,silica nanoparticles were functionalized by MPS and core-shell latexes were prepared using miniemulsion polymerization method.The effect of silica and MPS concentration on the properties of the latex films were further investigated.1.To enhance the compatibility of nano-silica particles and the polyacrylate matrix,hydrophilic silica nanoparticles were hydrophobic modified by grafting γ-methacryloxypropyl trimethoxysilane(KH-570)onto the surface.FTIR and TGA result indicated the successful grafting of MPS onto the silica surface.Dispersion analysis showed that MPS-functionalized silica nanoparticles can disperse into the monomer uniformly.Contact angle analysis confirmed that the hydrophilic surface of the silica nanoparticles change to hydrophobic after modification.2.The effect of silica concentration on the properties of latex film was investigated.First,the alkoxysilane-functionalized core-shell latexes were successfully synthesized via miniemulsion copolymerization of the butyl acrylate,styrene with γ-methacryloxypropyl trimethoxysilane as the functional monomer in the presence of the modified silica.TEM result showed that all the latex particles were core-shell structure.When these latexes dried at room-temperature,the post-crosslinking occurred due to the alkoxysilane groups on the particle surface and lead to the formation of the films.The morphology of the nanocomposite latexes and the mechanical properties,thermal properties,fire-resistant,optical properties and micro-structure of the resulted films were characterized.The stress at break、thermal and fire-resistant behaviors of the nanocomposite films were improved greatly by the incorporation of silica particles.SEM result showed most of the nanoparticles dispersed homogeneously in the polymer matrix and without obviously aggreation can be observed.3.The effect of MPS concentration on the properties of latex film was studied.The polymer/SiO2 nanocomposite emulsion were prepared by miniemulsion polymeization and then dried at room-temperatue.With increasing the amount of MPS,the degree of cross-link of the latex particles and latex film increased a lot.The tensile tests showed that stress at break of the nanocomposite films improved a lot compared with the pure latex film,however,the elongation at break decreased inevitably.The thermal and fire-resistant properties improved greatly with the increase of crosslinking degree.The optical test showed that the hybrid film was comparable to the pure polymer film.