Fluorescent Nanoporous Materials from Polypropylene-Based Covalent Adaptable Networks

Fluorescent polypropylene-based aerogels from thermoreversibly crosslinked networks have been developed. This facile and efficient synthesis results in low-cost, recyclable, chemically resistant, and highly porous functional materials. This process includes the chemical crosslinking of polypropylene, followed by thermal phase separation and freeze-drying, yielding aerogels with specific surface areas up to 200 m²/g, according to nitrogen absorption-desorption measurements. This is significantly higher than that previously reported for polypropylene porous materials. Besides characterizations of polymer networks by infrared spectroscopy and differential scanning calorimetry, a suite of analytical techniques was utilized to characterize the skeletal framework of aerogels, including scanning electron microscopy and small-angle X-ray scattering. These methods revealed the highly porous nanostructural features of interconnected 3D networks. The modulation of the excited-state properties of the incorporated luminophore is demonstrated and provides insights into their potential applications. Importantly, the aerogels have a pronounced ability to retain toluene, affecting their fluorescence behavior over an extended time scale. This conceptual study presents a low-cost solution for the preparation of highly porous materials that might offer versatility in functionality and may open the door to further exploration and design of high-performance materials that can act very effectively in the sensing and adsorption of organic molecules. The results also provide an intriguing direction for future research focusing on the molecular mechanisms driving the observed fluorescence modulations.