In the 1990s, researchers at Johns Hopkins University began investigating the chemical compounds that were used to coat coal tar.
A decade later, those compounds were used in cosmetics, paints, and plastics.
Since then, researchers have studied more than 70 chemicals, and their findings are now used to create synthetic fabrics and other materials.
The process of creating these synthetic materials is called biopolymerization, and it’s what’s behind the new plastic coatings we’re seeing in our oceans.
“You’ve got the polymerization of petroleum products, and then you’ve got plastics, and so on,” says Marcia McLean, a biopolymers scientist at the University of Texas at Austin.
The polymerization process involves forming tiny particles from a chemical solution, where the molecules are separated by a polymer membrane.
The membrane then bonds the molecules together, creating a thin film.
The material then undergoes chemical bonding, and that bond forms a bond with the membrane.
That bond allows the polymer to form a strong bond with a larger, less-rigid membrane, which then bonds to the polymer.
“We are really interested in the interaction of these materials,” McLean says.
The result of this process is a material that is less rigid than the original, and is able to be used in many different ways, like on skin, in textiles, and in medical applications.
“That’s what we call a polymeric membrane,” she says.
For a time, this process was used to make the popular soft, silky fabrics that were so popular in the 1990-2000s.
But McLean and her colleagues decided to go beyond soft fabrics and apply the process to a much more complex, hard material: coal tar, or tar.
The first use of coal tar came from the U.S. in the 1970s, when scientists used the compound to coat the tar in tar-covered steel pipe.
The oil-and-gas industry also used tar-based coatings to coat its tar-soaked pipelines.
After that, the process became common in many countries, and scientists in the United States started to use coal tar to coat tar-laden diesel exhaust pipes.
Coal tar coatings can be used to cover pipelines, and even as a coating on surfaces that are not exposed to oil or gas.
“The main thing we’re interested in is that we can apply the chemical to a variety of materials,” says McLean.
For example, a recent study at the National Institutes of Health looked at the impact of coal-tar coatings on a variety inorganic materials, including organic solids like silica and glass.
These materials, the researchers found, had a much better resistance to chemical corrosion than the traditional coatings used for tar-coated pipes.
“When we use coal-titanium coatings, the corrosion is less of an issue, and the coating actually gets better with time,” McLeod says.
“It’s a great example of how we can incorporate materials in a way that we’re really interested and have the potential to improve.”