Alginates (nickel alginate, NiA; copper alginate, CuA; zinc alginate, ZnA) and 3-aminopropyltriethoxysilane (APTES) were alternately deposited on a magnesium hydroxide (MH) surface by the spray-drying-assisted layer-by-layer assembly technique, fabricating some efficient and environmentally benign flame retardants (M–FR, including Ni–FR, Cu–FR, and Zn–FR). The morphology, chemical compositions, and structures of M–FR were investigated. With 50 wt % loading, compared with EVA28+MH, the peak heat release rate, smoke production rate, and CO production rate of EVA28+Ni–FR decreased by 50.78%, 61.76%, and 66.67%, respectively. The metals or metal oxide nanoparticles arising from alginates could catalyze the pyrolysis intermediates of EVA into graphene and amorphous carbon, which could bind the inorganic compounds (the decomposition products of MH and APTES) together and form some more protective barriers. For each M–FR, the flame retardant and smoke suppression efficiency were different, which were caused by the diverse carbonization and graphitization behaviors of three alginates. ZnA generated some ZnO aggregations and could not catalyze the graphitization of intermediates. For CuA, the catalytic graphitization was limited by the tightly binding graphene layer. As for NiA, the configuration of the Ni atom could not provide strong binding of Ni substrate and carbon. The liquid-like Ni nanoparticles could restructure and get out from firm graphene shells, so the catalytic graphitization of NiA was efficient and sustainable. This work displayed the catalytic graphitization mechanism of alginates while exploring a simple and novel strategy for fabricating efficient green flame retardants.

中文翻译：

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海藻酸钠，3-氨基丙基三乙氧基硅烷和氢氧化镁阻燃剂的喷雾干燥层合组装及其在乙烯-乙酸乙烯酯树脂中的催化石墨化作用

通过喷雾干燥辅助的逐层组装技术，将藻酸盐（镍藻酸镍，NiA；藻酸铜，CuA；藻酸锌，ZnA）和3-氨基丙基三乙氧基硅烷（APTES）交替沉积在氢氧化镁（MH）表面上，制造一些有效且对环境无害的阻燃剂（M-FR，包括Ni-FR，Cu-FR和Zn-FR）。研究了M-FR的形态，化学成分和结构。与EVA28 + MH相比，负载量为50 wt％时，EVA28 + Ni-FR的峰值放热率，烟雾产生率和CO产生率分别降低了50.78％，61.76％和66.67％。由藻酸盐产生的金属或金属氧化物纳米粒子可以催化EVA的热解中间体，形成石墨烯和无定形碳，它可以将无机化合物（MH和APTES的分解产物）结合在一起，并形成更多的保护性屏障。对于每种M-FR，阻燃剂和抑烟效果不同，这是由于三种藻酸盐的碳化和石墨化行为不同而引起的。ZnA生成一些ZnO聚集体，不能催化中间体的石墨化。对于CuA，催化石墨化受到紧密结合的石墨烯层的限制。对于NiA，Ni原子的构型不能提供Ni底物和碳的牢固结合。液态镍纳米粒子可以重组并从牢固的石墨烯壳中脱出，因此NiA的催化石墨化是有效且可持续的。