CO2-triggered reversible transformation of soft elastomers into rigid and highly fluorescent plastics

Abstract Polymers that alter their properties and functions in response to carbon dioxide (CO 2 ) exposure offer significant potential for the development of smart technologies and innovative CO 2 utilization approaches. Nonetheless, effectively regulating the behavior of solid-state polymers using CO 2 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 2 -vitrifiable polyethyleneimine and CO 2 -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 2 . 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 2 position the materials as innovative platforms for responsive mechanical systems and CO 2 -activated optical devices, with potential applications in sensing, display, and data storage technologies.