After decades of making the best glass for its function, manufacturers have begun to look to the next logical step for the most common glass: to make it more water resistant.
It’s no secret that some glass products have a tendency to degrade over time.
But new research shows that this problem can be alleviated by making the glass water-resistant, which could be a boon for a glass industry that is already struggling with water.
“Glass is not a monolithic material,” says Jamey Richter, who studies water-resilient glass at the University of Michigan and who was not involved in the new research.
“It has a lot of individual components that can be water-repellent.”
A common way to make water- and water-wicking glass is to use an organic compound called polyethylene glycol.
But this compound, when mixed with water, produces a water repellent compound that is more resistant to degradation than regular polyethylenes.
To make the polyethylenes water-proof, the glass manufacturer adds a layer of a material called nitrile that has the same chemical properties as the nitric acid that is present in vinegar.
But because nitriles are also a water-absorbing agent, they’re used as a solvent to help the glass absorb water.
A glass maker could then add another layer of the water-stabilizing substance called boron nitride.
This chemical also is used as an additive to glass that helps it resist water loss and helps the glass retain its shape over time, according to the researchers.
The next big step in water-sensing glass is a process called hydrophobic bonding, which uses a combination of carbon and an organic chemical to help glass absorb more water.
“When you use a hydrophilic substance, the water molecules interact with the hydrophiles and they become attracted to it,” says Richter.
“You get a kind of hydrophobia that is very similar to that of living cells.
So, this is what makes glass water resistant.”
It turns out that hydrophobicity is what keeps water molecules in glass, and this makes it water-sensitive.
But the water resistance can be achieved by using a new method called superhydrophobic boronic acid.
This material is more water-soluble than nitriels and is used in glass in addition to glass-forming compounds.
When mixed with regular borony acid, it turns into nitriolic acid, which is a water resistant chemical.
But it is a lot less water-like than the borolic acid that can also be found in vinegar, and that’s why it’s often used in other water-relieving materials, like glass, according the researchers, who published their findings this week in the journal Science Advances.
“These are compounds that are very water-specific, and so they have a high water-holding capacity,” says James Toulmin, the lead author of the paper.
“We wanted to find out if there was a way to convert these to a water source.
We found that these compounds could be converted into the superhydroglobic acid.”
The researchers tested several combinations of these materials in a lab experiment to see if the superborbic acid was water-binding.
The superhydrolobic acids that they used were also water-selective and water resistant, which meant that the water would not be drawn into the glass.
“In a laboratory environment, water does not tend to accumulate,” says Toulmine.
“But it also is very easy to create a problem with a water reservoir.”
The superboronic acids that the researchers used were not water-responsive.
But a variety of other materials, including glass and some organic compounds, could be.
They are a great starting point to make more water friendly products, says Richters team member Jennifer Kwan.
“There’s a lot to explore in terms of what these materials can do, but we’re definitely going to be looking for other applications for these materials,” she says.
But to get there, the team is looking to create an ultrahydrophobically active superborate, which they describe as a combination that would allow the superaborbic acids to interact with water molecules more easily.
In other words, they want to develop a material that could be used to make superhydrobic acid, and then convert it to a superborous acid.
That process could be useful in other applications, such as making superhydrocarbonic acid that would help with the production of superhydrogen, which are elements found in water.