College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fuzhou350108, P. R. China.
ACS Appl Mater Interfaces. 2023 Feb 1;15(4):5963-5973. doi: 10.1021/acsami.2c21279. Epub 2023 Jan 17.
The demands of safety and sustainability have driven the development of intrinsic flame-retardant biobased polymers from renewable materials. Herein, a mechanically robust, good flame-retardant, and recyclable thermoset was developed from renewable epoxidized soybean oil (ESO) by using 2-hydroxyethyl methacrylate phosphate (HEMAP) as the reactive flame retardant and tannic acid (TA) as the charring agent. The flame resistance of the obtained ESO-based thermoset achieved the highest UL-94 of V-0 rating and a limited oxygen index value of 26.7% due to the synergistic flame-retardant effect of phosphate and TA. The flame-retardant mechanisms of the gaseous phase and condensed phase were fully investigated by thermogravimetric infrared, scanning electron microscopy-energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and Raman spectra. It is confirmed that the incorporation of phosphate and TA could effectively promote the formation of dense carbon layers and delay the pyrolysis of long aliphatic chains. The ternary crosslinking of ESO, HEMAP, and TA via free-radical polymerization and epoxy-ring opening reaction resulted in a rigid network with a high crosslink density, bestowing the thermoset with superior tensile strength (20.0 MPa), flexural strength (36.3 MPa), and bonding strength (16.7 MPa on steel). Moreover, the ESO-based thermoset exhibited a fast stress relaxation behavior due to the transesterification of dynamic β-hydroxyl phosphate esters, which enables the network with thermal-healing ability and recyclability. This study explores a feasible method to prepare an intrinsic flame-retardant polymer from commercially available and renewable vegetable oils and natural polyphenols.
安全性和可持续性的需求推动了从可再生材料中开发内在阻燃型生物基聚合物。在此，通过使用 2-羟乙基甲基丙烯酸磷酸酯（HEMAP）作为反应性阻燃剂和单宁酸（TA）作为炭化剂，从可再生的环氧大豆油（ESO）制备了一种机械强度高、阻燃性能好且可回收的热固性聚合物。由于磷酸酯和 TA 的协同阻燃作用，所得的基于 ESO 的热固性聚合物的阻燃性能达到了 UL-94 最高 V-0 等级和 26.7%的极限氧指数值。通过热重红外、扫描电子显微镜-能量色散光谱、X 射线光电子能谱和拉曼光谱充分研究了气相和凝聚相的阻燃机理。证实了磷酸酯和 TA 的掺入可以有效地促进致密碳层的形成，并延迟长脂肪族链的热解。通过自由基聚合和环氧开环反应，ESO、HEMAP 和 TA 的三元交联形成了具有高交联密度的刚性网络，赋予热固性聚合物优异的拉伸强度（20.0 MPa）、弯曲强度（36.3 MPa）和粘结强度（钢上为 16.7 MPa）。此外，由于动态 β-羟基亚磷酸酯的酯交换反应，基于 ESO 的热固性聚合物表现出快速的应力松弛行为，使网络具有热修复能力和可回收性。本研究探索了一种从商业上可用的可再生植物油和天然多酚制备内在阻燃聚合物的可行方法。
