Fast char formation induced by POSS confining Co-MOF hollow prisms in epoxy composites with mitigated heat and smoke hazards
Fast char formation induced by POSS confining Co-MOF hollow prisms in epoxy composites with mitigated heat and smoke hazards
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DOI：
10.1016/j.cej.2023.145682
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发表时间：
2023-08
影响因子：
15.1
通讯作者：
Zhengde Han;Wenyuan Zhang;Xiaoning Song;H. Vahabi;Ye-Tang Pan;Wenchao Zhang;Rongjie Yang
中科院分区：
文献类型：
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作者：
Zhengde Han;Wenyuan Zhang;Xiaoning Song;H. Vahabi;Ye-Tang Pan;Wenchao Zhang;Rongjie Yang
含过渡金属的笼型倍半硅氧烷（POSS）具有优异的阻燃性能。然而，通过过渡金属钴（Co）与POSS直接配位获得的阻燃剂倾向于附聚，导致不令人满意的阻燃效率。本文设计了一种合成路线，以水溶性钴-聚乙烯吡咯烷酮（Co-PVP）配合物为模板和钴源，首先在其表面生长钴-金属-有机骨架（Co-MOFs），然后以Na-POSS水溶液作为结构导向剂和刻蚀剂，同步负载POSS和去除模板。最后，获得具有围绕Co-MOF包裹的POSS的中空棱镜（指定为Co-MOF@POSS）。空心结构不仅在基体中表现出优化的分散性，而且暴露出更多的活性中心，催化碳层的形成，POSS形成的二氧化硅陶瓷层进一步增强了碳层的强度。当Co-MOF@POSS添加量为环氧树脂的2wt%时，可获得优异的阻燃效果。Co-MOF@POSS的加入使环氧复合材料的极限氧指数提高到27.5%，热释放速率峰值、总热释放峰值和总发烟峰值分别降低了34.6%、16.6%和23.8%。本工作为MOF和POSS基阻燃剂的制备提供了新的思路。
Polyhedral oligomeric silsesquioxanes (POSS) containing transition metals have excellent flame retardant properties. However, the flame retardant obtained by direct coordination of transition metal cobalt (Co) with POSS tends to agglomerate, resulting in unsatisfactory flame retardant efficiency. Herein, a synthetic route was designed to use a water-soluble cobalt-polyvinylpyrrolidone (Co-PVP) complex as the template and cobalt source to first grow cobalt-metal–organic frameworks (Co-MOFs) on its surface, and then an aqueous solution of Na-POSS was used as both a structure-directing agent and an etching agent to load POSS and remove the template synchronously. Finally, a hollow prism with POSS wrapped around the Co-MOF (designated Co-MOF@POSS) was obtained. The hollow structure not only showed an optimized dispersion in the matrix but also exposed more active sites, catalyzing the formation of the carbon layer, and the silica ceramic layer formed by POSS further enhanced the strength of the carbon layer. An excellent flame retardant effect was obtained by adding Co-MOF@POSS to epoxy at 2 wt%. The heat release and smoke release of the epoxy composites were significantly reduced by the synergistic effect of cobalt and silicon, and the addition of Co-MOF@POSS improved the limiting oxygen index to 27.5% and decreased the peak of heat release rate, total heat release, and total smoke production by 34.6%, 16.6% and 23.8%, respectively. This work provides new ideas for the preparation of MOF and POSS-based flame retardants.