Biomimetic intensified NH/CH···π interaction via metal oxide-mediated interfacial polarization for robust...

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-Fe₃O₄) with an engineered electron-deficient interface via Fe₃O₄ integration. We revealed that Fe₃O₄ 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-Fe₃O₄ and π-electron-rich nanoplastics and enabled a dramatic ∼839-fold increase in porosity. Consequently, PUF-Fe₃O₄ achieved a high adsorption capacity for nanoplastics, striking 16-fold and 4.26-fold enhancement compared to Fe₃O₄ and pristine PUF, respectively and surpassing most powder adsorbents. The engineered interface also enabled superior mechanical resilience of PUF-Fe₃O₄, 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.