This study was carried out to investigate the hydrophobicity and dispersibility of fumed silica according to the addition amount of two kinds of surface modifiers, trimethylchlorosilane and hexamethyldisilazane. The surface modifiers used in surface modification process were added in an amount of 0~80wt% based on the weight of the fumed silica, Fourier transform infrared spectroscopy and Elemental analysis showed that the hydrophobicity of fumed silica is increased by increasing the addition amount of surface modifiers. To investigate the change in dispersibility of fumed silica as the hydrophobicity of fumed silica increases, Transmission electron microscopy and Particle size analysis were measured. As a result, it was confirmed that as the hydrophobicity of fumed silica increases, the cohesion between the particles of fumed silica is weakened so the dispersibility of fumed silica is improved and average particle size is decreased. In order to evaluate the modification stability of fumed silica, self-experiment was carried out. From the self-experimental result, it was confirmed that the hydrophobicity of hydrophobically modified fumed silica was maintained even after a certain time regardless of the addtion amount of the surface modifiers.

본 연구는 두 종류의 표면 개질제 trimethylchlorosilane(TMCS), hexamethyldisilazane(HMDZ)를 사용하여 fumed silica의 표면 개질 과정에서 첨가량 변화에 따른 소수성 및 분산성 변화에 대한 연구를 진행하였다. 표면 개질 과정에서 사용된 개질제는 fumed silica 중량 대비 0~80wt%로 첨가하였으며, FT-IR(Fourier transform infrared spectroscopy), EA(Elemental analysis) 분석을 통해 개질제의 첨가량이 증가함에 따라 fumed silica의 소수성이 증가함을 확인하였다. 그리고 fumed silica의 소수성이 증가함에 따른 분산성 변화 분석을 위해 TEM(Transmission electron spectroscopy), PSA(Particle size analyzer)를 측정하였다. 그 결과, fumed silica의 소수성이 증가함에 따라 fumed silica의 입자간의 응집력이 약화되어 분산성이 향상되고 평균 입자 크기 또한 감소하는 것을 확인할 수 있었다. Fumed silica의 개질 안정성을 평가하기 위해 자체 실험을 진행한 결과, 소수성 개질된 fumed silica의 경우 표면 개질제 첨가량과 관계없이 일정 시간 이후에도 소수성이 유지되고 있음을 확인하였다.