Xia He, Froimowicz Pablo, Salum Maria Laura, Smith Mitchell, Carter Jennifer, Ishida Hatsuo
Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States.
MRA Systems, LLC, 103 Chesapeake Plaza, Baltimore, Maryland 21220, United States.
ACS Omega. 2025 Mar 7;10(10):10662-10674. doi: 10.1021/acsomega.4c11620. eCollection 2025 Mar 18.
Aliphatic amine-based viscous benzoxazine resins that are liquid at or near room temperature have great potential for their ease of processability and raw material accessibility, which will play a significant role in large-scale industrial applications. In this study, eight aliphatic benzoxazines are synthesized by the traditional Mannich reaction under solventless conditions using linear diamines, branched diamines, or triamine and cycloaliphatic diamines with eugenol and paraformaldehyde. A recycling sample preparative size-exclusion chromatography (SEC) is used to obtain the purified products. H and C nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy are employed to study the molecular structure of all the aliphatic amine-based benzoxazines. Two exothermic peaks are commonly observed by differential scanning calorimetry (DSC) and are assigned to the oxazine ring-opening and eugenol allyl group polymerization as well as degradation of the allyl group in the eugenol part. The glass transition temperatures ( ) of all of the aliphatic amine-based polybenzoxazines are evaluated by DSC analysis of the polymers. The activation energy of the polymerization is determined by DSC at different heating rates from 2 to 20 °C/min and calculated by the Kissinger and modified Ozawa methods to be in the range of 102-134 kJ/mol. In addition, the thermal degradation and flammability properties of the polymer are monitored by thermogravimetric analysis (TGA) and microcombustion calorimetry (MCC), respectively. All the monomers showed initial degradation after 250 °C and low flammability with limiting oxygen index (LOI), heat release capacity (HRC), and total heat release (THR) values of 44.8, 77-153 J/g K, and 7.58-20.50 kJ/g, respectively. Among all of the aliphatic amine-based benzoxazines, the cycloaliphatic amine-based benzoxazine (EU-1,2dch) polymers show the best thermal stability and the highest , while tris-functional amine-based benzoxazine (EU-tapa) shows the smallest heat release capacity and the lowest due to their unique structures.
基于脂肪族胺的粘性苯并恶嗪树脂在室温或接近室温时呈液态，因其易于加工和原料易得而具有巨大潜力，这将在大规模工业应用中发挥重要作用。在本研究中，使用线性二胺、支化二胺或三胺以及脂环族二胺与丁香酚和多聚甲醛，通过传统的曼尼希反应在无溶剂条件下合成了八种脂肪族苯并恶嗪。采用循环样品制备尺寸排阻色谱（SEC）获得纯化产物。利用氢和碳核磁共振（NMR）光谱以及傅里叶变换红外（FTIR）光谱研究了所有基于脂肪族胺的苯并恶嗪的分子结构。通过差示扫描量热法（DSC）通常观察到两个放热峰，它们分别归因于恶嗪环开环和丁香酚烯丙基聚合以及丁香酚部分烯丙基的降解。通过对聚合物的DSC分析评估了所有基于脂肪族胺的聚苯并恶嗪的玻璃化转变温度（ ）。通过DSC在2至20℃/min的不同加热速率下测定聚合反应的活化能，并通过基辛格法和改进的小泽法计算得出其范围为102 - 134 kJ/mol。此外，分别通过热重分析（TGA）和微燃烧量热法（MCC）监测聚合物的热降解和燃烧性能。所有单体在250℃后开始降解，且具有低可燃性，其极限氧指数（LOI）、热释放能力（HRC）和总热释放（THR）值分别为44.8、77 - 153 J/g·K和7.58 - 20.50 kJ/g。在所有基于脂肪族胺的苯并恶嗪中，基于脂环族胺的苯并恶嗪（EU - 1,2dch）聚合物表现出最佳的热稳定性和最高的 ，而三官能胺基苯并恶嗪（EU - tapa）由于其独特的结构表现出最小的热释放能力和最低的 。
