Molecular Structure and Environment Dependence of Shear-Driven Chemical Reactions: Tribopolymerization of Methylcyclopentane, Cyclohexane and Cyclohexene on Stainless Steel
Molecular Structure and Environment Dependence of Shear-Driven Chemical Reactions: Tribopolymerization of Methylcyclopentane, Cyclohexane and Cyclohexene on Stainless Steel
复制标题
DOI：
10.1007/s11249-023-01703-w
复制
发表时间：
2023-04
影响因子：
3.2
通讯作者：
Yu-Sheng Li;S. Jang;Fakhrul H Bhuiyan;A. Martini;Seong H. Kim
中科院分区：
文献类型：
--
作者：
Yu-Sheng Li;S. Jang;Fakhrul H Bhuiyan;A. Martini;Seong H. Kim
摩擦化学是由剪切驱动的机械化学的另一个名称，研究复杂的动态界面过程，这些过程可能导致表面磨损或形成有益的摩擦膜。为了更好地了解这些过程的机理，我们在室温下研究了具有不同内环应变的有机分子（甲基环戊烷、环己烷和环己烯）在不锈钢（SS）表面上在惰性（N2）、氧化（O2）和还原（H2）环境下的摩擦聚合反应性。在干净的不锈钢表面，前驱体分子具有广泛的分子取向。在惰性和还原性环境中，无应变环己烷的摩擦化学活性最低。与n2环境相比，h2o2环境下的摩擦化学活性受到抑制。在o2环境下，只有环己烯产生摩擦膜和甲基环戊烷，而环己烷不产生。用拉曼光谱对摩擦膜进行分析，观察了类金刚石碳（DLC）和非晶碳（a-C）由于摩擦产物的光化学降解而产生的光谱特征。基于红外光谱，发现摩擦膜是含氧基团的有机聚合物。无论何时生产聚合物三角膜，磨损量都被抑制了几个数量级，但不会完全为零。这些结果支持了先前提出的摩擦聚合过程中涉及表面氧作为反应物的机制。图形抽象
Tribochemistry, which is another name for mechanochemistry driven by shear, deals with complex and dynamic interfacial processes that can lead to surface wear or formation of beneficial tribofilms. For better mechanistic understanding of these processes, we investigated the reactivity of tribopolymerization of organic molecules with different internal ring strain (methylcyclopentane, cyclohexane, and cyclohexene) on a stainless steel (SS) surface in inert (N2), oxidizing (O2), and reducing (H2) environments at room temperature. On the clean stainless steel surface, precursor molecules were found to physisorb with a broad range of molecular orientations. In inert and reducing environments, the strain-free cyclohexane showed the lowest tribochemical activity among the three molecules tested. Compared to the N2environment, the tribochemical activity in H2was suppressed. In the O2environment, only cyclohexene produced tribofilms and methylcyclopentane while cyclohexane did not. When tribofilms were analyzed with Raman spectroscopy, the spectral features of diamond-like carbon (DLC) or amorphous carbon (a-C) were observed due to photochemical degradation of triboproducts. Based on infrared spectroscopy, tribofilms were found to be organic polymers containing oxygenated groups. Whenever polymeric tribrofilms were produced, wear volume was suppressed by orders of magnitudes but not completely to zero. These results support previously suggested mechanisms which involve surface oxygen as a reactant species in the tribopolymerization process.Graphical Abstract