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溶 凝 膠 法

溶 凝 膠 法. 簡 介. 圖片轉載於 http://w ww.gaematech.co.kr/ sub2/sub2_main_02.html. 溶凝膠法的優缺點 優點 ： (1) 均質性與高純度。 (2) 節省能源，減少蒸發的損失與空氣的汙染、 較純的樣品、避開相變、結晶的過程。 缺點： (1) 原料昂貴。 (2) 凝膠的收縮量大。 (3) 孔穴、氫氧基、碳。. 溶凝膠法主要過程 ( 以 SiO 2 為例 ) TMOS+ 水 + 醇 (a) 水解 (hydrolysis) 反應。

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溶 凝 膠 法

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  1. 溶 凝 膠 法

  2. 簡 介 圖片轉載於http://www.gaematech.co.kr/ sub2/sub2_main_02.html

  3. 溶凝膠法的優缺點 優點： (1) 均質性與高純度。 (2) 節省能源，減少蒸發的損失與空氣的汙染、 較純的樣品、避開相變、結晶的過程。 缺點： (1) 原料昂貴。 (2) 凝膠的收縮量大。 (3) 孔穴、氫氧基、碳。

  4. 溶凝膠法主要過程(以SiO2為例) TMOS+水+醇 (a)水解(hydrolysis)反應。 (b)縮合(condensation)反應。 OR OR RO Si OR + H2O HO Si OR + ROH OR OR OR OR OR OR RO Si OH + HO Si OR RO Si O Si OR + H2O OH OR OR OR 溶 凝 膠 法 的 過 程 與 原理

  5. (c) 多縮合反應(polycondensation) OH OH HO Si O Si OH + 6Si(OH)4 OH OH OH OH Si OH HO Si OH HO OH OH O O O HO Si Si OH O Si Si O + 6(H2O) OH OH O O OH HO Si HO Si OH OH OH

  6. 聚合反應 三維網狀結構(3D network) 顆粒(particle) 單體(monomer) 鏈狀結構(chain)

  7. 不同環境下的聚合反應 10nm 10nm (acid-catalyzed) (base-catalyzed) (1) Far from gel point (2) Near from gel point (3) Gel point

  8. 溶凝膠過程與溫度之關係

  9. Effect of experimental condition on the gelling time • pH value • temperature • molar ration of H2O:Si • precursor molecules • volume ratio of ROH:H2O • solvent and additive

  10. Effect of pH value on the structure of gel

  11. Aging process

  12. Flow Chart of the two methods used to vary the pore characteristics of the gel silica matrices

  13. Drying

  14. Stage 1 CRP

  15. Falling rate period 1 FRP1 Falling rate period 2 FRP2

  16. Densification

  17. Example of preparation of lithium containing gel Hydrolysis of TEOS with LiNO3 solution and LiOH solution

  18. Infiltration of LiNO3/LiOH in SiO2 gel

  19. TG curves for the gels a: polymerized/LiNO3 gel b: infiltrated/LiNO3 gel c: polymerized/LiOH gel d: infiltrated/LiOH gel

  20. * Melting point of LiNO3 is 254oC

  21. Preparation of V2O5 crystals through sol-gel VO(i-OC3H7)3 or VOCl3 + C2H5OH+ H2O + dilute HNO3 pH~2 stir 1 day at 65oC dark green color 60oC oven for 4 weeks Dried gels dark green brown color Heat treated in oxygen atmosphere to varies temperatures brown color

  22. VOCl3 prepared gel V2O5 crystal forms above 200oC VO(i-OC3H7)3 prepared gel V2O5 crystal forms above 400oC

  23. VOCl3 prepared gel VO(i-OC3H7)3 prepared gel 200oC 400oC 700oC 700oC

  24. Alumina gel

  25. Hydrolysis The unhydrolyzed species [Al(OH2)6]+3 exist below pH 3. With increasing pH, [Al(OH2)6]+3 can be hydrolyzed extensively: [Al(OH2)6]+3+hH2O→ [Al(OH)h(OH2)6-h]+3-h+hH3O+ hH3O++hOH- →2hH2O Condensation X trimer Dimer

  26. Chemical modified Aluminum Alkoxides Al-tri-sec-butoxide Al(OC4H9)3 modified with -diketones Acteylactone (CH3COCH2COCH3, AcAcH) Benzoylacetone (CH3COCH2COC6H5, BzAcH) Ethyl acetoacetata (CH3COCH2COOC2H5, EAcAcH) The stabilization of -diketones for Al-tri-sec-butoxide in the order BzAcH < AcAcH < EAcAcH

  27. The Al2O3/BzAc gel film is the most stable in air and have the highest photosensitivity among Al2O3 gel films.

  28. ORMOSILS (Organically Modified Silicates) Si(OR)4+R2Si(OR)2+YR’Si(OC2H5)3 where R is alkyl group -CH3, R’ is alkylene group -(CH2)n Y is organofunction group such as -(CH2)3NH2, -(CH2)3NHCOONH2, -(CH2)3S(CH2)2CHO.

  29. Application: • Thin film and coating • 2. Monoliths • 3. Powders, grains, and spheres • 4. Fibers • 5. Porous gels and Members

  30. Some Systems have been studied • SiO2, Al2O3, B2O3, ZrO2, TiO2, Nb2O5, V2O5, Fe2O3, • P2O5, ZnO • 2. Binary : SiO2-Al2O3, Li2O-B2O3, P2O5-SiO2. • 3. Composite : CdS-SiO2, Pt-SiO2, organic-inorganic • hybrids, dye(R6G)-doped hybrids • 4. Multi-component: BaTiO3, PbZrxTi(1-x)O3, • (Pb(1-y)Lay)( ZrxTi(1-x))O3 (鐵電), YBa2Cu3O7 • Some Metal-alkoxides • TEOS (Si(OC2H5)4, 1L, 98%, USD $291), • TMOS (Si(OCH3)4), 100g, 98%, USD $100) • TPT (Ti(OCH(CH3)2)4, 500ml, 97%, USD $52), • TBZ ((Zr(OC4H9)4, 25g, 99%, USD $249), • ASB (Al(OC4H9)3, 500g 97% USD $64),

  31. End of Part One

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