EFFECT OF SURFACTANT ON SURFACE MODIFICATION OF CaCO3 NANOPARTICLES FOR LUBRICANT APPLICATION

초록

The adsorption behavior of laureth sulfonic acid (LSA) type surfactant on the calcium carbonate (CaCO3) substrate was investigated by a quartz crystal microbalance with dissipation monitoring (QCM-D), contact angle measurement, and zeta potential analysis. Additional tests such as Fourier transform infrared (FT-IR) spectrometry analysis and floating test have been conducted to evaluate the adsorption behavior of surfactant on the CaCO3 substrate. Contact angle measurement has shown a different wetting behavior depending on surfactant concentration. In a low surfactant concentration region, the CaCO3 surface becomes more hydrophobic with an increase in surfactant concentration due to monolayer adsorption of surfactant molecules on the solid surface. However, further increase in surfactant concentration after the formation of a monolayer saturated with surfactant molecules produced a reverse change from hydrophobic to hydrophilic due to bilayer formation of surfactant molecules on the CaCO3 surface. QCM-D measurement has been performed using quartz crystals coated with CaCO3 to observe mass of adsorbed surfactant molecules and viscoelastic properties of molecular layers. Visual floating test has shown a good agreement with measurements of contact angle and QCM-D.

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