Synthetic resins start out as viscous liquids that eventually solidify or "cure" into clear or translucent solids. These materials, which combine the desirable properties of strength, durability and light weight, are so useful that you can find them in thousands of applications, particularly aircraft, automobiles and electronic circuits. But for all that versatility, there's one thing that's remained elusive: once cured, resins can not be reshaped. Now, a team from France's National Center of Scientific Research (CNRS), led by award-winning physicist Ludwik Leibler, has developed an inexpensive and easily-produced material that is not only reshapable (like glass), but also repairable and recyclable, again, like glass. That's a potential boon for the auto body industry alone, and the possibilities for other uses are seemingly endless.
Way back in 1907, when Belgian chemist Leo Baekeland set out to create a replacement for shellac, he somehow ended up creating the world's first synthetic phenolic resin, Bakelite. Since then, the quest for lighter, cheaper, more resistant materials has continued apace, with the development of countless thermosetting plastic resins to replace heavier metal components. The CNRS team's compounds blend resin's most desirable properties with those of glass, while utilizing the same components already available industry-wide: epoxy, hardeners and catalysts.
Unlike traditional resins, the CNRS formulas, when subjected to high heat, can morph in shape without any change in the number of cross-links between their individual atoms. They can easily and endlessly transition from solid to liquid state and back again, which, until now, was a property only displayed by silica and a few other inorganic compounds.
Unheated, the resins can be made rigid or pliable by subtly changing the initial composition, which further expands the range of possible uses for these novel materials. We reported on another resin breakthrough earlier this year, and we'll keep you posted on the many new products that are sure to emerge from this important work in the months and years ahead.