졸-겔공정의 변수조절을 통해 제조된 유기-무기복합체 (PDMS/SiO  2   )의 미세구조와 특성

은희태; 황진명; Hee-Tai Eun; Chin-Myung Whang

Korean Journal of Materials Research, Vol.11, No.2, 94-103, February, 2001

Export Citation

졸-겔공정의 변수조절을 통해 제조된 유기-무기복합체 (PDMS/SiO 2 )의 미세구조와 특성

Microstructure and Properties of Organic-Inorganic Hybrids(PDMS/SiO 2 ) Through Variations in Sol-Gel Processing

은희태, 황진명

인하대학교 재료공학부

Hee-Tai Eun, and Chin-Myung Whang

Materials Science and Engineering, Inha University, Inchon, 402-751, Korea

초록

졸-겔공정을 이용하여 SiO 2 및 TEOS에 유기 고분자로서 PDMS가 도입된 PDMS/SiO 2 xerogel을 제조하고 촉매로서 HCI과 NH 4 OH를 이용한 2 step acid/base catalyzed공정에 의해 SiO 2 및 PDMS/SiO 2 xerogel의 기공 크기 및 분포를 제어하였다. 촉매로서 HCl이 첨가된 SiO 2 및 PDMS/SiO 2 xerogel에서 PH는 2.3~2.5, gel화 시간 12~13일, xerogel의 모양은 Pellet형태를 나타내나 HCl/NH 4 OH 몰비가 증가하면 pH 및 gel화 시간은 급격히 감소하고 xerogel의 모양도 pellet형과 column형으로 뚜렷하게 구분된다. 이는 반응의 최종용액이 산성이면 가수분해속도가 축합속도보다 빠르게 진행되어 9el화에 오랜 시간이 소요되어 pellet형의 Xerogel이 되나 약산성에서는 축합속도가 가수분해속도보다 빠르게 되어 gel화 시간은 빨라지고 column형의 xerogel이 되기 때문이다 SiO 2 및 PDMS/SiO 2 , xerogel의 표면적 및 평균기공크기는 HCl/NH 4 OH 몰비가 증가함에 따라 각각 400 → 600( \m 2 /g)과 15 → 28 \AA 으로 변화하고 단일 기공크기분포를 갖는다. 이는 초기에 HCl에 의해 가수분해된 종이 NH 4 OH에 의해 축합속도가 촉진되어 silica의 골격구조가 낮은 온도에서 규칙적으로 형성되고 열처리에 의해 균일한 기공으로 되었기 때문이다.

SiO 2 and PDMS/SiO 2 xerogels which are derived PDMS into TEOS have been synthesized by sol-gel process and controlled pore size and distribution through 2 step acid/base catalyzed processes using HCI and NH 4 OH as a catalyst. In HCl catalyzed SiO 2 and PDMS/SiO 2 xerogels, pH and gellation time of xerogel were 2.3~2.5 and 12~13 days, respectively, and the shape of xerogel was identified to pellet type and column type. Under acidic condition of final reaction solution, the hydrolysis rate is accelerating, resulting in long gel times. The shape of xerogel is pellet type. In contrast, under less acidic condition, the condensation rate is accelerating, resulting in shorter gel times and the shape of xerogel is column type. The surface area and average Pore size were changed 400 → 600( \m 2 /g) and 15 → 28 \AA , respectively, depending to the increase of the mole ratio of HCl/NH 4 OH, and represented uniform pore size distribution. It is that all the alkoxide groups are hydrolyzed by HCl after the first step and the condensation rate is enhanced by NH 4 OH. The regular backbone structures of silica are formed at low temperature and the uniform pores are produced by heat treatment.

Keywords:Sol-gel;PDMS/SiO 2;xerogel;FT-IR spectroscopy;BET;SEM

[References]

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[2] Mackenzie JD, Chung YJ, Hu Y, J. Non-Cryst. Solids, Rubbery ORMOSILs and Their Applications, 147-148, 271 (1992)

[3] Ishizaki K, Komarneni S, Nanko M, Porous Materials-processing technology and application, pp. 67-172, Kluwer Academic Pub., 1998 (1998)

[4] Guo L, Lee JH, Beaucage G, J. Non-Cryst. Solids, Structural Analysis of Poly (dimethylsiloxane) Modified Silica Xerogels, 203, 61 (1997)

[5] Kramer SJ, Alonso FR, Mackenzie JD, 'Organically Modified Silicate Aerogels', pp. 295 in Better Ceramics Through Chemistry VII, ed. by Coltrain BK, Sanchez C, Schaefer DW, Wilker GL. MRS435, 1996 (1996)

[6] Schmidt H, 'Organically Modified Ceramics-Materials with 'History' or 'Future?', pp. 409 in Ultra-structure Processing of Advanced Materials, ed. by Ulhmann DR, Ulrich DR, John Wiley & Sons, NY, 1992 (1992)

[7] Brinker C, Scherer G, Sol-Gel Science, Aca-demic Press, Boston, 1990 (1990)

[8] Huang HH, Orler B, Wilker GL, Macromol, Structure-Property Behavior of New Hybrid Materials Incor-porating Oligomeric Species into Sol-Gel Glasses. 3. Effect of Acid Content, Tetraethoxysilane Con-tent and Molecular Weight of Poly (dimethylsiloxane), 20, 1322 (1987)

[9] Ying JY, Benziger JB, J. Non- Cryst. Solids, Structure Tailoring of Alkoxide Silica, 147-148, 222 (1992)

[10] Iler R, The Chemistry of Silica, John Wiley & Sons, NY, 1979 (1979)

[11] Gonzalez-Oliver CJR, James PF, Rawson H, J. Non-Cryst. Solids, Silica and Silica-Titania G lasses Prepared by the Sol-Gel Process, 48, 129 (1982)

[12] Gawaguchi T, Hishikura H, Iura J, Kokubu Y, J. Non-Cryst. Solids, Monolithic Dried Gels and Silica Glass Prepared by the Sol-Gel Process, 63, 61 (1984)

[13] West R, Inorganic Polymers, pp. 141-185, Pren-tice Hall, New Jersey, 1992 (1992)

[14] Bertoluzza A, Fagnano C, Morelli MA, J. Non-Cryst. Solids, Raman and Infrared Spectra on Silica Gel Evolv-ing Toward Glass, 48, 117 (1982)

[15] Decottignies M, Phalippou J, Zarzycki J, J. Mater. Sci., 13, 2605 (1978)

[16] Tohge N, Moore GS, Mackenzie JD, J. Non-Cryst. Solids, Structural Developments during the Gel to Glass Transition, 63, 95 (1984)

[17] Duran A, Serna C, Fornes V, Fernandez Navarro JM, J. Non- Cryst. Solids, Structural Considerations about SiO 2 Glasses Prepared by Sol-Gel, 82, 69 (1986)