Research Stories

by Nicholas Gerbis

Nobody likes having the rug pulled out from under them. But it can be a good experience for a scientist. Setbacks lead to new questions. The search for answers can provide valuable information that ultimately advances the area of study.

Consider the case of Arizona State University chemist C. Austen Angell. All was well until he became aware that the nanoconfined water data he had been using to support his ideas were not providing the information he thought they were. What to do? Probe further. Ask more questions.

Angell delved into the nanoscale research literature. He pulled together findings that showed that nanoconfinement at the level needed to stop water from crystallizing greatly distorted the glass transition of normal glassformers. This raised questions as to whether such data should be used at all.

"I realized that the problems with nanoconfinement studies were not restricted to water," says Angell, an ASU Regents Professor of Chemistry.

Angell says the problem is apparent even in traditional glassformers like toluene. Toluene is a common solvent used in paint thinners and adhesives. Under normal conditions, toluene undergoes a classical glass transition at 115 degrees K (-252.7 F). The transition is accompanied by a typically huge jump in heat capacity.

Everything changes when you place toluene into a 2.4 nanometer structure. The sharp transition disappears completely.

"Toluene is a substance that doesn't have any sort of order-disorder transition, just a glass transition," Angell says. "But when you put it inside something with these tiny pores, that glass transition signal gets all smeared out horribly."

Angell decided that he could not base his conclusions about the nature of water on nanoporous confinement studies. He would have to fall back on traditional thermodynamics to extract any useful information about water in ‘no-man's land.' In the process, he also identified a problem that could have set physical chemistry back had it gone unchecked.

Scientists, to paraphrase the Rolling Stones, don't always get what they want; but diligence and a commitment to validity will sometimes give them what they need.

Read more about Angell's work on glass formation in "A glassy riddle: solving the mystery of water glass."