🧪 Sulfur for innovative plastics

Scientists at the CNRS have developed a new family of stable sulfur-containing polymers capable of emitting light without the addition of dye. This work, published in Angewandte Chemie, paves the way for new functional materials and plastic films with unprecedented properties.

Plastics, ubiquitous in our daily lives, are made of polymers, these large molecules or chains formed by the repetition of elementary building blocks called monomers. The most common ones, called commodity plastics, are polyethylene or polypropylene, formed solely from carbon and hydrogen atoms.


Introducing other atoms along the polymer chain backbone or in side groups allows access to enhanced functionalities; these are referred to as specialty or (multi)functional polymers. Among them, those containing sulfur generate significant interest because this electron-rich atom can confer original optical, chemical, or mechanical properties to the material.

In many sulfur-containing polymers, the distribution of sulfur atoms along the polymer chain is poorly controlled. These sulfur polymers are amorphous, soft, and have low heat resistance, which severely limits their performance and applications. The key challenge therefore lies in developing molecular building blocks capable of ensuring a regular arrangement of sulfur atoms along the chain.

This is what scientists from the Institut de science des matériaux de Mulhouse (CNRS/Université Haute-Alsace), the Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau (Germany), and the Leibniz-Institut für Verbundwerkstoffe GmbH (IVW) have just achieved.

To accomplish this, the scientists designed a new molecular building block that "programs" in advance the regular spacing of sulfur atoms in the future polymer chain. Under light irradiation, this block reacts quickly with simple sulfur compounds to form stable polymers while maintaining a highly ordered arrangement of the sulfur atoms. This light-induced reaction can be carried out under mild conditions and in the absence of a metal catalyst while rapidly reaching high molecular weights and conversion rates.

The resulting polymers are semi-crystalline materials stable even at high temperatures. But even better: under ultraviolet irradiation, they emit light without the addition of fluorescent dye.

This light emission stems from the regular arrangement of sulfur atoms within the material, which enables unique electronic interactions. This phenomenon opens up prospects for applications in optics, sensing, or the field of functional materials.

Beyond the new properties demonstrated, this work is part of a broader reflection on efficient and resource-lean synthesis processes that can contribute to the development of higher-performance and more sustainable plastics, better suited to current technological and environmental challenges.

Editor: CCdM