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Biomimetic intensified NH/CH···π interaction via metal oxide-mediated interfacial polarization for robust nanoplastics capture by polyurethane foam
Summary
Researchers engineered a magnetic polyurethane foam by integrating iron oxide nanoparticles that polarize adjacent N-H and C-H bonds, amplifying non-covalent interactions with nanoplastics and achieving a 16-fold higher adsorption capacity than iron oxide alone, with easy magnetic regeneration avoiding energy-intensive centrifugation.
Precise manipulation of non-covalent interaction to control the binding strength was paramount for nanoplastics capture. However, conventional powder adsorbents not only suffered from weak non-covalent interaction with nanoplastics, resulting in low adsorption capacity, but also required energy-intensive recovery during recycling. Mimicking how biological system employed precise charge distribution to enhance molecular recognition, we developed a magnetic polyurethane foam (PUF-FeO) with an engineered electron-deficient interface via FeO integration. We revealed that FeO formed the interfacial Fe-N/O coordination bonds and covalent Fe-O-C linkage with the PUF backbone. These tailored interfacial bonds induced the polarization of adjacent N-H/C-H bonds to amplify non-covalent N-H/C-H···π interactions between PUF-FeO and π-electron-rich nanoplastics and enabled a dramatic ∼839-fold increase in porosity. Consequently, PUF-FeO achieved a high adsorption capacity for nanoplastics, striking 16-fold and 4.26-fold enhancement compared to FeO and pristine PUF, respectively and surpassing most powder adsorbents. The engineered interface also enabled superior mechanical resilience of PUF-FeO, allowing facile and low-energy regeneration via magnetic separation (without high-speed centrifugation) and compression. Crucially, the generality of strategy was confirmed using CuO, validating this powerful biomimetic principle for adsorption/separation, molecular recognition/assembly and beyond.