Sticks and Stones May Break Bones, But Not this Nanocomposite Windshield

It starts with a piece of road debris — usually a small stone or bit of gravel that turns into a dangerous projectile when you're cruising down the highway — and it ends with a frustrated driver shouting expletives at the windshield.

Crack.

If you're lucky, and you catch it early enough, it's just a small chip that can be repaired. Unfortunately, that's not what happened for me. A few years ago, a small chip, practically invisible to me, evolved into a star-shaped blemish that later grew into a full-grown crooked line that stretched across my old car's windshield. Yes, I should've gotten it repaired way before it had time to get worse, but "life is so busy" or something like that.

I drive a different car today, with a crack-free windshield, but a startup called Alchemy in Kitchener, Ontario, is aiming to prevent the costly, time-consuming and frustrating task of windshield replacement altogether.

To do so, the company has created a 5-mil transparent film that is applied to the exterior of a windshield. The film, called ExoShield, is manufactured using master rolls of PET for improved impact resistance, with a nanocomposite — a "hard coat" — applied to both sides using a roll-to-roll coating process.

"The general principle is glass is scratch resistant, but it's brittle, it breaks. Polymers like PET or polycarbonate are impact resistant, but they scratch very easily," Khanjan Desai, Alchemy co-founder, said in a phone interview. "What Alchemy is doing is we've developed a nanocomposite that's allowing us to improve the scratch-resistance performance of a material like PET, so that it can be used in applications where we couldn't use it before."

Desai started Alchemy with co-founder Chong Shen as part of a fourth-year design project at the University of Waterloo in Waterloo, Ontario. Desai and Shen both studied nanotechnology engineering. The two students initially created a passive coating under the name Neverfrost, which prevented frost on windshields, but realized the coating needed to be more durable for automotive applications.

"Ideally, as we get this [ExoShield] coating to be better and better, we would like to reintegrate the anti-frost coating technology in there as well," Desai said.

The company says ExoShield increases a windshield's impact resistance by six times and blocks 99.9 percent of ultraviolet radiation, protecting a passenger's or driver's skin as well as the vehicle's interior.

"[PET] can be applied on many brittle materials to increase impact resistance because it can absorb and distribute the impact energy when something strikes that object," Desai explained. "In addition, it has really high optical qualities, which is necessary for an automotive application."

PET can also be stretched — a characteristic that prevents ExoShield from looking wrinkled and creased. For a more visual example, Desai said to imagine wrapping gift wrap around a basketball: "You'll get all of these creases," he described.

"When you're working with the complex curvature of the windshield where you have curvature from both top to bottom and side to side, you need to be able to selectively sort of shrink the film, so that a flat film can turn into this complex curvature," he said, adding that the film can be heated in select areas to avoid creases during the installation process.

ExoShield launched in the United States and Canada in August 2017. The product is currently available at 85 dealers — usually businesses that do window tinting, detailing, etc. — across the two countries and in 25 major cities. By the end of April, Desai estimated that ExoShield will be available at more than 100 dealers.

"Our goal is to be over 300 by the end of this year," he said.