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The nylon 6 (PA6)/polyurethane (PU) debris produced during the sanding process would result in a serious resource waste and environmental hazard if disposed of inappropriately. Therefore, this study proposed a simple process for separating and recycling PA6 and PU components of PA6/PU debris. Results revealed that the instantaneous dissolution of PU in N,N-dimethylformamide was independent of temperature and time but related to the quantity of the solvent. Further investigation showed that 43.2% of waste PA6/PU debris was dissolved at room temperature, with pulp density of 10% and within 10 minutes, indicating that PA6 and PU could be quickly separated from the waste PA6/PU debris. In addition, proton nuclear magnetic resonance indicated that the dissolved PU could be recovered by selective precipitation-stripping using an equal amount of deionized water. Moreover, the chemical structure analysis disclosed that the PU in PA6/PU debris should be polyether PU synthesized by reacting with methylene diphenyl diisocyanate and polyether polyols. Besides, the stable chemical structure and thermal properties of separated samples observed from differential scanning calorimetry and thermogravimetry results confirmed that the recycling products could be reused as recycled plastic materials.

The development of sustainable polyimides (PIs) from abundant renewable biogenic feedstocks has been limited by the bio-based content and the lack of mechanical and thermal properties. This study synthesized a series of daidzein-based PIs with a high bio-based content of up to 53%, which was significantly higher than the reported bio-based content (approximately 40%). The mechanical and thermal stability of the obtained polymer is comparable with that of commercial PIs, with the tensile strength of 148.6 MPa and the glass transition temperature (T g ) of 318.2 °C. Additionally, the daidzein-based PIs showed excellent fluorescence characteristics with a maximum fluorescence efficiency of 45.18 ns and an absolute fluorescence quantum yield of 14.1%. Such a performance combination has not been reported in bio-based PIs, even petrochemical PIs. Interestingly, the integration of experiments and density functional theoretical calculations revealed an effective intermolecular and intramolecular conjugation and the inhibition effect of intramolecular charge transfer by "enone and ether bonds" in daidzein-derived PIs. This work provides a possible route for the design and synthesis of multifunctional PIs with high bio-based content.

Metallic Bi, as an alloying‐type anode material, has demonstrated tremendous potential for practical application of potassium‐ion batteries. However, the giant volume expansion, severe structure pulverization, and sluggish dynamics of Bi‐based materials result in unsatisfied rate performance and unstable cycling stability. Here, 2D bismuth@N‐doped carbon sheets with BiOC bond and internal void space (2D Bi@NOC) are successfully fabricated via a self‐template strategy to address these issues, which own ultrafast electrochemical kinetics and impressive long‐term cycling stability for delivering an admirable capacity of 341.7 mAh g−1 after 1000 cycles at 10 A g−1 and impressive rate capability of 220.6 mAh g−1 at 50 A g−1. Particularly, the in situ transmission electron microscopy observations visualize the real‐time alloying/dealloying process and reveal that plastic carbon shell and void space can availably relieve dramatic volume stress and powerfully maintain structural integrity. Density functional theory calculation and ultraviolet photoelectron spectroscopy test certify that the robust BiOC bond is thermodynamically and kinetically beneficial for adsorption/diffusion of K+. This work will light on designing advanced high‐performance energy materials and provide important evidence for understanding the energy storage mechanism of alloy‐based materials.

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