In-Situ Fabrication of Biobased Fluorescent Coumarin-Derived Nanohybrids in the POE Matrix for Tailored Multifunctionality

Although polyolefin elastomer (POE) has achieved widespread industrial applications, its intrinsic functional homogeneity critically constrains performance in high-end application scenarios. To address this limitation, the biobased vinyl coumarin derivative (EC) was synthesized in this study. The fluorescent POE/EC films were subsequently fabricated via in situ grafting technology, achieving nanoscale dispersion of EC within the POE matrix. The as-prepared POE/EC films not only retained EC’s fluorescence characteristics but also maintained the high transparency (>90% transmittance in the visible spectrum). Furthermore, the corresponding multifunctional performance, including water vapor transmission rate (WVTR), volume resistivity, and yellowness index variation under UV aging, was systematically characterized. The 0.25 wt % EC loading reduced the WVTR by 9.40%. The 1.00 wt % loading of EC can enhance the volume resistivity by 549.63% and the 0.75 wt % loading of EC leads to a 269.64% reduction in yellowness index variation following 200 h of accelerated UV aging compared with the pristine POE film. The implementation of POE/EC films in photovoltaic cells as a representative case study showed that POE/0.75%EC-encapsulated cells achieved a 0.19 mA·cm^–2 improvement. Such tailored multifunctionality based on the structures and loadings of EC nanohybrid in POE unlocks pathways for POE materials in high-performance fields.