100 Nano-Stories: What’s the Best Silylating Reagent for Surface Modification of Aerogels?

Episode #16: MTMS/TEOS, & EtOH Reagents Explained!

Carlos Manuel Jarquín Sánchez
4 min readJan 21, 2021
Photo by Interesting Engineering.


Wait, wait, Carlos! What are these chemicals like TMOS and Reagents? You’re confusing me!

Oh, dear! Don’t worry, reader! I’ll explain all of these details in my previous article, where we explain some of the main precursors and molecules in the silica gel!

However, the concept you will want to consider is the meaning of a Silyating Reagent!

Silyation is a process where we replace hydrogen (H) from a hydroxyl group (OH) with a hydrophobe to make the surface of a silica gel non-polar, which makes the aerogel repel water.

A Reagent means that it is a substance for use in chemical analysis to test if a chemical reaction had occurred.

Cool, Carlos! Now can we talk about the chemistry of aerogels? Plus, can we play around with some of the chemicals, Carlos?

Just kidding, you won’t blow up! Photo by ImgFlip.com

Silyation & Its Reagents

Now that we know what silyation is, let’s talk about what silyation will replace in the silica aerogel!

Silyation will replace the hydrogen of the hydroxyl group (OH group) on the surface of the silica aerogel with an alternative silicon atom (SiR3) to create a hydrophobic (non-polar) aerogel!

But, Carlos, what about the chemicals! Don’t go into another rabbit hole! Stay on task! 😮

Thank you, reader! Nearly caught me off guard there!

Now we reach the process where Surface Modification plays a role in manufacturing Hydrophobic Aerogel!

We take a silylating reagent such as a trimethylsilyl group.

But what is a trimethylsilyl group? In the name, we see that there is a methyl group, otherwise known as the chemical CH3.

Hey, Carlos! That was in the last article! I starting to see where the pieces of the surface modification come into play!

But “tri” means “three.” So this means that there are 3 methyl groups or 3 molecules of CH3. Finally, we have “silyl”. What this means is that all of these 3 methyl groups are connected to a silicon atom (Si) to form the chemical compound trimethylsilyl group.

Trimethylsilyl Groups! (Si + CH3) Photo by Wikipedia.

But there are other silylating reagents on the market for surface modifications for silica aerogel?

But what types of silyating reagents, Carlos?

Some of the most common silylating reagents on the market for silica aerogels are Methyltrimethoxysilane (MTMS) and Trimethylchlorosilane (TMCS)/Ethanol (EtOH).

MTMS Reagent!
TMCS Reagent!

Wait, Carlos, this reminds me of an article you previous made! You talked about Optical Properties of a Silica Aerogel!

Photo by Twitter.

Let me guess, you’re either going to make an article on properties of aerogels or the properties of the silyating agent. I am right, Carlos!


OOPS! Photo by Wordpress.com

To Be Continued. . .

Vocabulary 📓

Silyation → The process where we replace hydrogen in the Si-OH groups and replace it with a hydrophobe.

Reagent → A substance for use in chemical analysis.

Trimethylsilyl Group → 3 methyl groups are connected to a silicon atom (Si) to form the chemical compound (trimethylsilyl group).

Methyl Group → CH3. CH3 is a molecule similar to methane (CH4), but you remove one hydrogen atom.

Solvent → A liquid/solid substance that is dissolved to form a solution.

Connect: 🔗




© 2021 by Carlos Manuel Jarquin Sanchez. All Rights Reserved.