졸-겔 공정으로 제조한 나노 실리카의 표면개질 및 분산성에 관한 연구 = Study on surface modification and dispersion of silica nanoparticles prepared by sol-gel process

다국어 초록 (Multilingual Abstract)

Silica nanoparticles are widely used in a myriad of applications such as electronics, construction, paints, food, and paper to enhance mechanical, electrical, and thermal performance. Recent interest in surface treatment of silica nanoparticles has surfaced to improve compatibility with organic matrices.
In this thesis, we achieved hydrophobicity of silica surface (fumed silica and sol-gel silica) by reacting it with hexamethyldisilazane (HMDS) or hexadecyltrimethoxysilane (HDTMS) by tailoring various reaction parameters. The surface treatment of silica was quantified by thermogravimetry and elemental analysis.
In the case of reaction for fumed silica with HMDS, the optimum reaction conditions (temperature and time) in decalin were determined to be 200 ℃ and 6 h, respectively in terms of dispersity in toluene and surface roughness of the silica-hydrophobic epoxy composite film.
In addition, we fabricated surface-treated silica nanoparticles by sol-gel process. Prior to the surface treatment, silica nanoparticles were obtained by sol-gel process from tetraethyl orthosilicate (TEOS). Subsequently, the synthesized silica nanoparticles were surface-treated by a coupling reaction with octyltrimethoxysilane (OTMS) or HDTMS under various reaction conditions. The combination of sol-gel process in ethanol at 50 ℃ for 24 h and the surface treatment at 50 ℃ for 2 h showed the most enhanced dispersity in organic solvents, thereby leading to the lowest surface roughness of the silica/epoxy composite film, determined by scanning electron microscope-energy dispersive x-ray spectrometer, thermogravimetry and elemental analysis. The surface modification of silica reduced the oxygen permeability of the composite film by 12%.

목차 (Table of Contents)

• Ⅰ. 서론 1
• Ⅱ. 실험 9
• 1. 시약 및 기기 9
• 2. Fumed silica를 사용한 소수성 실리카 합성 10
• 1) HMDS에 의한 개질 10
• 2) HDTMS에 의한 개질 11
• 3. Sol-gel silica를 사용한 소수성 실리카 합성 11
• 1) HMDS에 의한 개질 11
• 2) HDTMS에 의한 개질 12
• 3) In-situ 방식의 OTMS 및 HDTMS에 의한 개질 13
• 4. 표면 조도 측정 14
• Ⅲ. 결과 및 고찰 15
• 1. Fumed silica를 사용한 소수성 실리카 합성 15
• 1) HMDS에 의한 개질 15
• (1) 분산성 16
• (2) SEM 분석 17
• (3) EA, TGA 분석 18
• (4) 표면 조도 평가 21
• 2) HDTMS에 의한 개질 22
• (1) SEM 분석 22
• (2) TGA 분석 23
• 2. Sol-gel silica를 사용한 소수성 실리카 합성 25
• 1) HMDS에 의한 개질 25
• (1) Fumed silica와의 비교 25
• (2) SEM 분석 26
• (3) TGA 분석 27
• (4) 표면 조도 평가 28
• 2) HDTMS에 의한 개질 29
• (1) SEM 분석 29
• (2) TGA 분석 29
• (3) 표면 조도 평가 31
• 3) In-situ 방식의 OTMS 및 HDTMS에 의한 개질 31
• (1) 분산성 33
• (2) SEM, BET 분석 34
• (3) FT-IR 분석 37
• (4) SEM-EDS, EA, TGA 분석 38
• (5) 표면 조도 평가 40
• 3. 산소 차단성 효과 42
• Ⅳ. 결 론 44
• Ⅴ. 참 고 문 헌 46