Mei Wan,Congling Shi,Lei Chen,Lei Deng,Yueping Qin,Honglei Che,Jingyun Jing,Junyi Li,Xiaodong Qian
Ammonium polyphosphate (APP) is the most commercially valuable phosphorus-based flame retardant, but poor interaction with the polymer interface limits the flame-retardant efficiency. In this work, a new type of multi-layered nanomaterial coating APP (APP-PEI@MXene@ZIF-67) was prepared and introduced into thermoplastic polyurethane (TPU) polymers by a simple and green assembly strategy. The effects of different loading shells of modified APP on the flame retardancy of TPU composites were investigated, as well as their gas/condensed phase thermal degradation products and their flame-retardant mechanisms. The results showed that APP-PEI@MXene@ZIF-67 was more favorable for catalytic char formation than APP, and the residual char formed by its composites was denser and more continuous. Compared with the pure TPU, the pHRR, THR, pSPR, and TSP of TPU/APP-PEI@MXene@ZIF-67–2BL composites were decreased by 72.75 %, 87.25 %, 59.58 %, and 85.97 %, respectively, which significantly reduced the heat and smoke release during the combustion process. The gas-phase and condensed-phase flame retardant mechanisms synergized to construct a possible approach to address the fire risk and heat/smoke hazards of TPUs and promote the extensive application of TPU polymers.
Gold nanoparticles (AuNPs) can be used to improve the performance of propagating surface plasmon resonance (PSPR) refractive index sensors. The resonant coupling effect between PSPR and localized surface plasmon resonance (LSPR) supported by AuNPs on sensitivity remains to be elucidated in terms of evanescent field intensity and distribution. In this study, we directly compare the sensitivity of the PSPR sensor and the resonant coupling mode between the PSPR and LSPR sensors in the wavelength scanning mode. The sensitivity of PSPR can be significantly improved in the near-infrared region excitation wavelength. 1,6-Hexanedithiol was used to achieve a AuNP modified gold film (GF-AuNP). The PSPR excited by the prism coupling mechanism can effectively stimulate LSPR supported by AuNPs in the GF-AuNP, and then resonant coupling is generated. Compared with PSPR, the resonant coupling mode shows a decrease in penetration depth by 28 times and an increase in the surface electric field intensity by 4.6 times in the numerical simulations. The decrease in the penetration depth in the GF-AuNP is made at the expense of bulk sensitivity. The biosensing sensitivity of the GF-AuNP shows up to 7-fold improvement in the carcinoembryonic antigen immunoassay and the GF-AuNP is proven to be a better biosensor. The experimental measurements are in excellent agreement with the theoretical model. This study can be also considered as a guide for the design of plasmonic sensors for detecting multiple substances at different scales, such as cells and proteins.
危险品化学品经营许可证（带存储）