溶凝膠法製做玻璃

1. OR OR OR HO Si OR + ROH RO Si + H2O OR OR OR OR OR OR OR O OR RO Si OH + HO Si RO Si Si + H2O OR OR OH OR 溶凝膠法製做玻璃 溶凝膠法的過程與原理:以SiO2為例 TMOS(Si(OCH3)4)+水+醇 (a)水解(hydrolysis)反應 • (b)縮合(condensation)反應

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

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

4. 10nm (1) Far from gel point 10nm (2) Near from gel point (3) Gel point (acid-catalyzed) (base-catalyzed) 不同環境下的聚合反應

5. 溶凝膠過程與溫度之關係

6. xerogel film dense film heat coating Metal alkoxide solution xerogel dense ceramics wet gel coating heat evaporation hydrolysis condensation aerogel evaporation of solvent gelling uniform particle sol precipitating spinning furnace ceramic fiber 溶凝膠的不同製程與結果

7. 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) 殘留孔穴、氫氧基、碳。

8. 影響成膠時間的因素 1. 溶液酸鹼值 2. 溫度 3. 矽前驅物與水的莫耳比 4. 矽前驅物的分子量 5. 醇類與水的體積比 6. 其他溶劑與添加物

9. 熟化過程(Aging process) acid-catalyzed base-catalyzed particulate silica gels high solubility particulate silica gels low solubility

10. 緻密化(Densification)

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

14. Alumina gel

15. ORMOSILS (Organically Modified Silicates) Si(OR)4+R2Si(OR)2+yR′Si(OC2H5)3 where R is alkyl(烷基) group( -CH3), R′ is alkylene group(烯烴基-(CH2)n), y is organofunction group such as -(CH2)3NH2, -(CH2)3NHCOONH2, - (CH2)3S(CH2)2CHO.

16. Basic NMR Interactions in Solids NMR: Nuclear Magnetic Resonance The Hamiltonian of the interaction of the nucleus with external magnetic field B0 and its environment: H=HZ + HQ + HC + HD Where HZ is the Zeeman interaction, HQ is the quadrupole interaction, HC is the chemical shift interaction, and HD is the magnetic dipole-dipole interaction.

19. FT FT

20. Quadruploe interaction- first order First order quadrupole powder pattern for spin I=3/2

21. Quadrupole Interaction- second order Second order quadrupole powder pattern for central transition of a spin I=3/2

23. 3Si+1B 4Si 27Al MAS spectrum of 9Al2O3-2B2O3 B0=40T 11B MAS spectrum of borosilicate glass B0=14.1T

24. Chemical shift interaction Chemical shift powder pattern

26. Magnetic dipole-dipole interaction In practice, it is very difficult to carry out a calculation of the lineshape due to dipole-dipole interaction. An excellent approximation for many cases is made by using a normalized Gaussian shape function given by

27. 7 Tesla

28. 14 Tesla 21.1 Tesla

29. The 45 Tesla Hybrid superconducting magnet of 11.5 tesla with a resistive magnet of 33.5 tesla

30. Magic Angle Spinning (MAS) probe rotor

31. Second order quadrupole interaction Chemical shift interaction

32. The structural groups of alkali silicate glasses determined from 29Si MAS-NMR (Journal of Non-Crystalline Solids 127 (1991) 53-64) 29SI MAS-NMR spectrum of sodium metasilicate glass. 29Si MAS-NMR spectra of sodium silicate glasses.

33. Experimentally determined Q, distribution in lithium (△), sodium (□) and potassium (○) silicate glasses as a function of moll% of alkali oxide. Fitted lines were calculated from equilibrium constants shown in table. , Q4; , Q3; , Q2； , Q1, , Q0.

34. Conclusion: The detailed distribution of the structural units Qn in binary silicate glasses was determined by means of the MAS-NMR technique. The equilibrium of the following types were found apparently to govern the concentrations of Qn species, 2Qn Qn-1 + Qn+1 (n = 3, 2, 1), of n = 3, 2, 1 for sodium and potassium and n = 3, 2 for lithium silicate glasses in limited composition ranges. The agreements with the thermodynamic data were quantitative in the sodium and potassium silicates but only qualitative in the lithium silicate. The chemical shift for all Qn, species depends linearly on the composition and the slopes are less for Qn, with smaller n. The linear relations between the averaged chemical shift and the theoretical optical basicity strongly suggest the potential use of the 29Si chemical shift as a scale for the basicity of the system.

35. Structure of sodium aluminoborate glasses study by NMR (Solid State Nuclear Magnetic Resonance 27 (2005) 37–49) 27Al B=18.8T 11B B=14.1T

36. 17O B=14.1T

37. Random mixing model: In a random mixing model without any constraints. 4–4 avoidance model: In this model, connections between tetrahedral network units, [4]M–[4]N (avoidance of [4]Al–O–[4]Al, [4]Al–O–[4]B and [4]B–O–[4]B species) are unfavorable, involving only trivalent cations (B and Al). oxygen containing [5,6]Al three-coordinated

38. Conclusions: Details of linkages such as [4]Al–O–[4]Al, [3]O(2[5,6]Al,[4]Al), [4]Al–O–[4]B, [4]Al–O–[3]B, [5,6]Al–O–[3]B, [4]Al–O–[4]B, [4]B–O–[3]B and [3]B–O–[3]B and B-NBO can be distinguished. The fractions of oxygen species can be calculated with the known fraction of B and Al species based on random mixing and mixing considering 4–4 avoidance (avoidance of [4]Al–O–[4]Al, [4]Al–O–[4]B and [4]B–O–[4]B species). All of the glasses in this study show high degrees of bond regularity (higher fractions of Al–B pairs than random) resulting from the ‘‘maximum 4–4 avoidance’’. However, the significant amounts of [4]Al–O–[4]B suggests that the [4]Al–O–[4]B is energetically less unfavorable than [4]Al–O–[4]Al and [4]B–O–[4]B. A better approach to predicting the oxygen speciation for the glasses containing significant amounts of [5,6]Al involves grouping two [5,6]Al species. The result strongly suggests the presence of [3]O(2[5,6]Al, [4]Al).