Hello colleague, I'm from Brazil. I am a master's student in Materials Science. I wonder if you could answer at least one question listed below: 1- Why hydrolysis and condensation of tetraethyl orthosilicate (TEOS) results in polymeric gel in acidic media and particulate gel (spherical SiO2 particles) in basic media? 2- Why we use acid/base catalysts in the sol-gel preparation of SiO2 from tetraethyl orthosilicate? 3- Why we use ethanol in the sol-gel preparation of SiO2 from tetraethyl orthosilicate?
First, let me try to explain your 2nd and 3rd doubts; 2. We know, the catalysts boost up the reaction mostly, The ammonia base is added to hydrolyze TEOS faster than water, as the OH ions forms effective nucleophile. The faster hydrolyzing of more Silanol monomers are obtained. The silanol monomers attaches with more siloxane bridges and after condensation, it breaks to form siilica NP and ethanol. 3. Ethanol and ethanol monomers would form an environment so that, the ethoxyl groups in the siloxane bridge would deprotonate and form ethanol and water during condensation and the steric hinderance will be low for the above process if it is surrounded by ethanol. Though I`m not sure for your first query, I think the stable gel is formed by acid catalyst and the deprotonation may not happen to give out sio2. Thanks and cheers! For your reference go through -- "Han, Y., Lu, Z., Teng, Z., Liang, J., Guo, Z., Wang, D., … Yang, W. (2017). Unraveling the Growth Mechanism of Silica Particles in the Stöber Method: In Situ Seeded Growth Model. Langmuir, 33(23), 5879-5890."
Hi. I want to ask. How about zinc acetate dihidrate and oxalic acid ? I try to make it become gel but it didnt work. It become percipitate. Can you help me ?
What are components and ratios that are used to make this into gel?.procedure to make it into a gel? i need this for replica fabrication .Please replay.
Sheldon Cooper, is that you?😂
Hello colleague, I'm from Brazil. I am a master's student in Materials Science. I wonder if you could answer at least one question listed below:
1- Why hydrolysis and condensation of tetraethyl orthosilicate (TEOS) results in polymeric gel in acidic media and particulate gel (spherical SiO2 particles) in basic media?
2- Why we use acid/base catalysts in the sol-gel preparation of SiO2 from tetraethyl orthosilicate?
3- Why we use ethanol in the sol-gel preparation of SiO2 from tetraethyl orthosilicate?
First, let me try to explain your 2nd and 3rd doubts;
2. We know, the catalysts boost up the reaction mostly, The ammonia base is added to hydrolyze TEOS faster than water, as the OH ions forms effective nucleophile. The faster hydrolyzing of more Silanol monomers are obtained. The silanol monomers attaches with more siloxane bridges and after condensation, it breaks to form siilica NP and ethanol.
3. Ethanol and ethanol monomers would form an environment so that, the ethoxyl groups in the siloxane bridge would deprotonate and form ethanol and water during condensation and the steric hinderance will be low for the above process if it is surrounded by ethanol.
Though I`m not sure for your first query, I think the stable gel is formed by acid catalyst and the deprotonation may not happen to give out sio2.
Thanks and cheers! For your reference go through -- "Han, Y., Lu, Z., Teng, Z., Liang, J., Guo, Z., Wang, D., … Yang, W. (2017). Unraveling the Growth Mechanism of Silica Particles in the Stöber Method: In Situ Seeded Growth Model. Langmuir, 33(23), 5879-5890."
Great video!
Excellent
Sir i can hear only the fan in the background
Hi. I want to ask. How about zinc acetate dihidrate and oxalic acid ? I try to make it become gel but it didnt work. It become percipitate. Can you help me ?
Good video
Is this followed by calcination?
thank you
continue bro
How much did you use? 😅 i can't find any quick gel
What are components and ratios that are used to make this into gel?.procedure to make it into a gel? i need this for replica fabrication .Please replay.
Sorry i want to ask, what kind of catalyst used for this method?
I think he used HCl🤔
How to make sol-gel TiO2 thin film to dip-coat fiber
why do u want to make it into a dip-coat fiber?
I want to know how you make it in few minutes
I have TEOS and Ethanol. what another to use to make it fast enough
Ahmed Mandor hcı and nh4oh and water. teos:water ratio must be 1:4
Pl, what is the ratio of hcl, nh4oh and water
ethanol to water 1:1, TEOS to water 1:4, I used .4ml 6M HCl, and added NaOH until I got a PH of 7. It formed in around 20 mins.
1. did you mix when you did this experiment or did you just add and wait as in the video 2. Molar of NaOH ?
@@shellyroof4903 what volume of ethanol do you recommend? And what concentration of NaOH?
ohh yeah :D
😂
pogi
what is the catalyst
Katalizör tepkimeyi hızlandırır ve hiçbir değişikliğe uğramadan çıkar@@yohansvarghese7115