Engineering Research Center for Nanomaterials , Henan University , Kaifeng 475004 , China.
School of Material Science and Engineering , Henan Polytechnic University , Jiaozuo 454003 , China.
Langmuir. 2019 Mar 26;35(12):4342-4352. doi: 10.1021/acs.langmuir.9b00093. Epub 2019 Mar 12.
In this article, 3-(3,5-di- tert-butyl-4-hydroxyphenyl) propionic acid (DBHP)-functionalized ZnO (DBHP-ZnO) nanoparticles were synthesized by decomposing the organometallic precursor Zn(DBHP) under alkaline conditions. This in situ surface modification method can induce small-sized ZnO nanoparticles (5 nm) and form strong linkage between DBHP and ZnO nanoparticles. DBHP as an organic compound hindered phenol antioxidant that not only improved the dispersion stability of the prepared DBHP-ZnO nanoparticles in the lubrication oil but also scavenged free radicals produced during the oxidation process of oil. Compared with DBHP, the thermal stability of the prepared composite antioxidant was greatly enhanced by introducing inorganic ZnO nanoparticles, which was proved by the results of the thermogravimetric analysis test. A rotary oxygen bomb test, pressurized differential scanning calorimetry, and free-radical-scavenging method all showed that DBHP-ZnO nanoparticles had better antioxidant properties than DBHP under high temperature in the base oil of di- iso-octylsebacate (DIOS). The activation energy of the oxidation process was used to analyze this result by the model-free methods, including the Flynn-Wall-Ozawa method and the Kissinger equation. The calculated results showed that DIOS containing DBHP-ZnO nanoparticles have the lowest reaction constant and the longest half-life period compared to those of individual DBHP and ZnO nanoparticles, which is attributed to the combined action of the organic-inorganic composites. Besides, DBHP-ZnO nanoparticles as the additive are able to improve the antiwear ability of DIOS to some extent. Therefore, the as-prepared DBHP-ZnO nanoparticles with desired dispersibility as well as better thermal stability and antioxidant ability than DBHP in the DIOS base oil could be a potential high-performance nanocomposite additive for a synthetic lubricant base oil like DIOS.
在本文中，通过在碱性条件下分解有机金属前驱体 Zn(DBHP)，合成了 3-(3,5-二叔丁基-4-羟基苯基)丙酸(DBHP)-功能化 ZnO(DBHP-ZnO)纳米粒子。这种原位表面改性方法可以诱导形成小尺寸的 ZnO 纳米粒子(5nm)，并在 DBHP 和 ZnO 纳米粒子之间形成强键合。DBHP 作为一种有机受阻酚类抗氧化剂，不仅提高了制备的 DBHP-ZnO 纳米粒子在润滑油中的分散稳定性，而且还能清除油氧化过程中产生的自由基。与 DBHP 相比，通过引入无机 ZnO 纳米粒子，大大提高了制备复合抗氧化剂的热稳定性，这通过热重分析测试的结果得到了证明。旋转氧弹试验、加压差示扫描量热法和自由基清除法均表明，在二异辛基癸二酸酯(DIOS)基础油中，DBHP-ZnO 纳米粒子在高温下比 DBHP 具有更好的抗氧化性能。通过非模型方法，包括 Flynn-Wall-Ozawa 法和 Kissinger 方程，用氧化过程的活化能来分析这一结果。计算结果表明，与单独的 DBHP 和 ZnO 纳米粒子相比，含 DBHP-ZnO 纳米粒子的 DIOS 具有最低的反应常数和最长的半衰期，这归因于有机-无机复合材料的协同作用。此外，DBHP-ZnO 纳米粒子作为添加剂，能够在一定程度上提高 DIOS 的抗磨性能。因此，与 DBHP 相比，具有良好的分散性、更好的热稳定性和抗氧化能力的所制备的 DBHP-ZnO 纳米粒子在 DIOS 基础油中可能是一种潜在的高性能纳米复合添加剂，适用于 DIOS 等合成润滑剂基础油。
