Programming Responsiveness: From Stimuli-Controlled Systems to Sustainable Polymer Materials
Dr. Céline Calvino, University of Freiburg, DE
Responsive materials—defined as systems that adapt their properties in a predictable manner under external stimuli such as light, temperature, or mechanical force—offer a powerful framework to encode function, extend material lifetimes, and enable more sustainable use of resources. In this lecture, I will present a unified research trajectory that establishes responsiveness as a central design variable, where stimuli act as control parameters from the molecular to the macroscopic scale.
I will first introduce early strategies based on supramolecular and dynamic covalent interactions to engineer polymer systems with emergent functionalities. These include mechanoresponsive materials that translate mechanical stress into optical signals for damage sensing, as well as encapsulated chemistries that enable stress-triggered release of functional agents for self-reporting or on-demand debonding. In parallel, dynamic covalent approaches for the in situ functionalization of cellulose nanocrystals during melt processing will be presented, addressing dispersion challenges and enabling mechanically reinforced, bio-based composites through scalable routes.
Building on this foundation, I will then present recent advances in photoreversible polymer systems based on quinolinone chemistry, enabling catalyst-free polymerization with near-quantitative reversibility. These systems allow repeated depolymerization–repolymerization cycles, with oxygen-mediated control over activation wavelengths and efficient solid-state cycloreversion. Importantly, this work establishes orthogonal control over material states, where light, heat, and environmental conditions selectively trigger distinct, non-interfering transformations within a single system.
Together, these approaches demonstrate how responsiveness can be programmed at the molecular level to control macroscopic behavior. By integrating dynamic interactions and orthogonal stimuli-responsive chemistries, this work outlines a general strategy to design adaptive materials that sense, respond, and enable circular use, paving the way toward more sustainable polymer technologies.
