Preparation method for low-density hydrophobic Al2O3 aerogel
An airgel and hydrophobic technology, which is applied in the field of inorganic oxide preparation, can solve the problems affecting optical and electrical properties, affecting the application of airgel, easy to absorb moisture, etc., and achieves the reduction of density and shrinkage, and the effect is obvious , the effect of simple operation
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[0017] A low-density hydrophobic Al 2 o 3 The preparation method of airgel, adopts two kinds of silylating reagents to carry out surface modification to the wet gel in aging process, comprises the steps:
[0018] Step 1: Prepare Al by sol-gel method 2 o 3 wet gel;
[0019] Step two, to the Al prepared in step one 2 o 3 Add ethanol to the wet gel for liquid sealing, age at 25-60°C for 5-72 hours, and then remove the ethanol;
[0020] Step 3, the Al prepared in step 2 2 o 3 The wet gel was immersed in an acetonitrile-ethanol solution above 30v / v%, solvent replacement was performed at 25-60°C for 5-72h, and then the solution was removed; at 25-60°C, Al 2 o 3 The wet gel was immersed in 30v / v%~80v / v% TEOS acetonitrile solution for surface modification for 5~72h, the solution was removed, and then Al 2 o 3 The wet gel is immersed in 1v / v%~2v / v% TMCS acetonitrile solution for surface modification for 5~72h, remove the solution or at 25~60℃, Al 2 o 3 The wet gel was imme...
Embodiment 1
[0024] Example 1 (first TEOS modification, then TMCS modification)
[0025] 1. To the above-mentioned Al prepared by sol-gel method 2 o 3 A small amount of ethanol was added to the wet gel to seal the surface of the wet gel, aged at 40° C. for 24 h, and then the ethanol was removed.
[0026] 2. Add 50v / v% acetonitrile-ethanol solution to cover the wet gel, perform solvent replacement at 40°C for 24h, then remove the solution; add 50v / v% TEOS solution to cover the wet gel at 40°C , surface modification for 24 hours, remove the solution, then add 1.85v / v% TMCS acetonitrile solution to cover the wet gel, surface modification for 24 hours, remove the solution; at 40°C, add acetonitrile to cover the wet gel, soak for 24 hours, The solution is then removed.
[0027] 3. Drying by organic solvent sublimation drying method, wherein the organic solvent is acetonitrile, the vacuum degree is 80-90kp, the temperature is 50°C, and the drying time is 24h, and the modified Al 2 o 3 airge...
Embodiment 2
[0028] Example 2 (simultaneous modification of TEOS+TMCS)
[0029] 1. To the above-mentioned Al prepared by sol-gel method 2 o 3 A small amount of ethanol was added to the wet gel to seal the surface of the wet gel, aged at 40° C. for 24 h, and then the ethanol was removed.
[0030]2. Add 50v / v% acetonitrile-ethanol solution to cover the wet gel, perform solvent replacement at 40°C for 24h, and then remove the solution; at 40°C, add acetonitrile solution mixed with TEOS and TMCS (the concentration of TEOS is 50v / v%, the concentration of TMCS is 1.85v / v%) submerged the wet gel, surface modified for 24h, and removed the solution; at 40°C, add acetonitrile to submerge the wet gel, soak for 24h, then remove the solution .
[0031] 3. Dry by the same method as in Example 1 to obtain the modified Al 2 o 3 airgel.
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