Nano-particle gel

• Main Authors: Yi-Ting Chiang, 江宜庭
• Other Authors: Heng-Kwong Tsao
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/79334273360214582619

碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 98 === In general, nano-particles can be suspended in solution due to Brownian motion. Although van der Waals attractions between particles may lead to aggregation, they are not strong enough to form particle network. Typically, upon the addition of polymers, particle gel can be formed by depletion forces. In this work, we show that silicon carbide (SiC) particles are able to form nanoparticle gel in polar solvent ethylene glycol (EG) by the addition of hydrogen-bond forming surfactants. When the surfactant dodecylamine (DDA) is added, the SiC/EG system changes from uniform nano-particle suspension to sediment in the presence of clear solution. According to the rheological measurements, the storage modulus is greater than the loss modulus, i.e., G’ > G’’. That is, upon DDA addition, the sediment displays gel-like behavior. As two SiC particles covered with DDA are nearly in contact, hydrogen bonds can be formed between the primary amine head groups (-NH2) and thus result in interparticle attraction. On the basis of the same mechanism, we show that the addition of dodecanic acid, that possesses the same carbon chain length but different head group (-COOH) from DDA, can lead to the formation of nano-particle gel as well. In addition to the nano-particle gel induced by the addition of hydrogen-bond forming surfactants, we also observe the formation of nano-particle gel in surfactant-free solvent. The examples include SiC nano-particles in decane, ZnO nano-particles in EG, and ZrO2 nano-particles in water or EG. The possible mechanism responsible for particle gel induced by solvent is proposed.