engleski

STRUCTURE FORMATION IN APST-SiO2 MIXTURES

Aminopropylsilanetriol (APST) is one of the most frequently used organofunctional silane coupling agents. This molecule also emerges through the hydrolysis of other alkoxysilanes as a product of hydrolysis. Because of its two functional groups located at the opposite molecular sites, it can react with organic polymers as well as with inorganic substrates and fillers. Its functionality greatly depends on the conformation of the molecule through the number of the available OH and NH bonds. Amorphous pirogenic silica Aerosil 200 is frequently used as nanofiller for rubbers and different plastics. It reduces the sedimentation rate, strengthens the elastomers and disperses well in polymeric matrices. Silica nanoparticles have silanol groups at the surface and siloxane bonds inside the particles. The SiOH groups at the surface of the neighboring particles interact through hydrogen bonds creating three dimensional lattice like structure. In order to get hydrophobic silica and to prevent nanoparticles to interact among themselves their surface is frequently modified with organosilane compounds. In this work we investigate different structures that were formed in APST-SiO2 mixtures with different contents of silica nanoparticles. Two kinds of mixtures were prepared. In the first one the SiO2 nanoparticles were mixed in 25% water solution of APST. The second mixture was prepared from the APST that has already been solidified by slow evaporation of water, and then again dissolved in water. This procedure enabled us to get some oligomeric structures of APST with reduced number of available OH bonds. Thus obtained structures were then investigated by micro-raman spectroscopy and monitored by SEM.

aminopropylsilanetriol; conformation; hydrogen bond

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