Steven Holdcroft | Plastics, Basically

Holdcroft began by acknowledging the weight of this topic—“The good, the bad and the ugly,” as he put it. In modern society, we are painfully aware of the bad: the magnitude of greenhouse gas emissions and waste that have become hallmarks of our single-use society. Pictures of floating masses of plastics, as large as small islands, in our oceans certainly remind us of the ugly. But in a lecture filled with optimism, Holdcroft emphasized the good.

One of the first uses of commercial plastics was in the production of billiard balls which were, until the early 20th century, made of ivory harvested from elephant tusks. The invention of the plastic celluloid allowed cheap, mass-scale manufacturing, a discovery that likely saved a species on the brink of extinction. But innovation did not stop at billiard balls. Plastics became not just a replacement for traditional materials, but an improvement on them. And so, as Holdcroft said, “chemists have become a victim of their own success.” But despite earning a dirty reputation among the environmentally conscious, the development of plastics is essential in bringing Canada’s net-zero carbon plans to fruition.  

Hydrogen is set to play a crucial role in that plan. Molecules of hydrogen gas store an incredible amount of chemical energy, just as energy is stored within molecules of carbon-based fuels like gasoline and coal. By combining hydrogen and oxygen gases in a device called a fuel cell, this energy can be harvested as electricity. The advantage? Unlike other fuels which form carbon dioxide when combusted, the process produces water as the only product.   

Almost every G7 country has a strategy to move toward hydrogen energy. (Information on Canada's strategy can be found here.) But the ambitious targets laid out in these strategies require massively scaling up fuel cell production. A flourishing hydrogen economy also requires green sources of hydrogen fuel. This necessitates further development of electrolyzers, which can use renewable energy to create hydrogen from water.  

A particular class of plastics, capable of replacing the harsh acidic and caustic solutions once found in hydrogen fuel cells and electrolyzers, has now become an integral part of both devices. Using thin sheets, rather than liquid, to separate the chemical reactions creates a safer, more compact design with higher efficiencies. It is these plastics that Holdcroft and his research group study.  

For the plastics replacing caustic solutions in particular, development has not been easy. Strongly basic solutions cause plastics to disintegrate as hydroxide ions (OH-) rip apart the chemical structure, leaving behind degraded material. But Holdcroft has devised an ingenious solution to this problem. His recent developments to the plastic polybenzimidazole (PBI) have created a groundbreaking new class of materials. Using simple chemical principles, Holdcroft and his group modified PBI to create a positively charged polymer chain capable of transporting basic hydroxide ions. The crucial step was incorporating two strategically placed carbon groups that sit like two outstretched arms shielding the atom most vulnerable to degradation. This has resulted in a plastic Holdcroft admits he never thought would be possible just a mere 10 years ago.  

This breakthrough material inspired an SFU spinoff company, Ionomr. Started by three of Holdcroft’s former students, Ionomr is commercializing the plastic for hydrogen fuel cells and electrolyzers. It may also be used in devices that capture carbon dioxide from the air and convert it to new useful products.

In the discussion that followed Holdcroft’s lecture, SFU president Joy Johnson asked him about his optimism. He credits the many discoveries that have been made in the past 10 years, including those in his own lab. I think most of us are ready to embrace this optimism. In his slides, Holdcroft shows a familiar graph: a hockey stick-shaped line recording atmospheric carbon dioxide concentration versus time. I first saw this data 15 years ago as a teenager in a movie theatre watching An Inconvenient Truth. Looking at this plot, I find my eyes drifting backwards through the years, tracing the line that connects that moment to today. The sense of urgency that drove me to pursue science then has only amplified. But urgency does not mean failure. We can feel inspired seeing the once-hazy path toward hydrogen becoming clear.