生物基官能化金属有机骨架(Bio-FUN-MOFs)由于其多途径阻燃机理和绿色合成过程而在阻燃领域的候选人群中脱颖而出。然而,探索和设计Bio-FUN-MOFs往往会抵消损害MOFs本身阻燃优势的问题,这不可避免地导致了资源的浪费。在这里,提出了一种通过酸碱平衡对MOFs进行生态调节的策略,用于由两只鸟用一块石头可控地制备Bio-FUN-MOFs,即,更高的阻燃元素负载和更多MOF结构的保留。具体来说,通过生物基碱精氨酸的弱蚀刻在ZIF-67的外围产生缓冲层,以抵抗负载磷源时植酸对ZIF-67的过度蚀刻,并尽可能保持内部晶体的完整性。作为概念的证明,在不存在精氨酸的情况下,ZIF-67几乎完全被植酸蚀刻掉。通过该策略获得的精氨酸和植酸官能化的具有卵黄@壳结构的ZIF-67(ZIF@Arg-Co-PA),作为一种生物基阻燃剂,降低聚脲复合材料的火灾危险。在只有5重量%的负载下,ZIF@Arg-Co-PA赋予聚脲复合材料的极限氧指数为23.2%,和热释放速率的峰值,总放热,烟气总量分别减少了43.8%,32.3%和34.3%,分别,与纯聚脲相比。此外,所制备的聚脲复合材料具有可接受的机械性能。这项工作将阐明具有出色防火安全性的聚合物复合材料的先进结构设计,特别是环保和高效的生物基MOF阻燃剂。
Biobased-functionalized metal-organic frameworks (Bio-FUN-MOFs) stand out from the crowd of candidates in the flame-retardant field due to their multipathway flame-retardant mechanisms and green synthesis processes. However, exploring and designing Bio-FUN-MOFs tend to counteract the problem of compromising the flame-retardant advantages of MOFs themselves, which inevitably results in a waste of resources. Herein, a strategy in which MOFs are ecologically regulated through acid-base balance is presented for controllable preparation of Bio-FUN-MOFs by two birds with one stone, i.e., higher flame-retardant element loading and retention of more MOF structures. Specifically, the buffer layer is created on the periphery of ZIF-67 by weak etching of biobased alkali arginine to resist the excessive etching of ZIF-67 by phytic acid when loading phosphorus source and to preserve the integrity of internal crystals as much as possible. As a proof of concept, ZIF-67 was almost completely etched out by phytic acid in the absence of arginine. The arginine and phytic acid-functionalized ZIF-67 with yolk@shell structure (ZIF@Arg-Co-PA) obtained by this strategy, as a biobased flame retardant, reduces fire hazards for polyurea composites. At only 5 wt % loading, ZIF@Arg-Co-PA imparted polyurea composites with a limiting oxygen index of 23.2%, and the peaks of heat release rate, total heat release, and total smoke production were reduced by 43.8, 32.3, and 34.3%, respectively, compared to neat polyurea. Additionally, the prepared polyurea composites have acceptable mechanical properties. This work will shed light on the advanced structural design of polymer composites with excellent fire safety, especially environmentally friendly and efficient biobased MOF flame retardants.