CO<sub>2</sub>-triggered reversible transformation of soft elastomers into rigid and highly fluorescent plastics.

Miwa, Yohei; Okada, Kazuma; Hayashi, Takumi; Hashimoto, Kei; Okubo, Hikaru; Takase, Hiroshi; Yamamoto, Katsuhiro; Nakano, Ken et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Polymers that alter their properties and functions in response to carbon dioxide (CO<sub>2</sub>) exposure offer significant potential for the development of smart technologies and innovative CO<sub>2</sub> utilization approaches. Nonetheless, effectively regulating the behavior of solid-state polymers using CO<sub>2</sub> remains a considerable challenge, highlighting the need for robust and reliable strategies to address this issue. This study presents elastomers that feature nanophase-separated morphologies composed of CO<sub>2</sub>-vitrifiable polyethyleneimine and CO<sub>2</sub>-permeable polydimethylsiloxane components. The elastomers (Young's modulus (E) of approximately 1 MPa) reversibly transform into hard plastics (E > 2 GPa) in the presence of CO<sub>2</sub>. In addition to bulk stiffening, their surface adhesion and friction rapidly shift, and the material's fluorescence is significantly amplified. Here, we show that these multifunctional responses to CO<sub>2</sub> position the materials as innovative platforms for responsive mechanical systems and CO<sub>2</sub>-activated optical devices, with potential applications in sensing, display, and data storage technologies.