文献类型：期刊文献

英文题名：Detailed insights of polydimethylsiloxane (PDMS) degradation mechanism via ReaxFF MD and experiments

作者：Wang, Junjie[1];Li, Guixiang[1];Zhang, Zhe[1];Huang, Qingfu[1];Niu, Bo[1];Zhang, Yayun[1];Long, Donghui[1]

机构：[1]East China Univ Sci & Technol, Key Lab Specially Funct Mat & Related Technol, Minist Educ, Shanghai 200237, Peoples R China

年份：2024

卷号：488

外文期刊名：CHEMICAL ENGINEERING JOURNAL

收录：;EI(收录号：20241515870148);WOS:【SCI-EXPANDED(收录号:WOS:001218448000003)】；

基金：This work was financially supported by National Natural Science Foundation of China (Nos. 22008073, 22078100, and 21878091) , and Shanghai Sailing Program (20YF1410600) .

语种：英文

外文关键词：PDMS; ReaxFF MD; Pyrolysis; Kinetics; Mechanism

摘要：Polydimethylsiloxane (PDMS) serves as a widely used silicone polymer in ablative thermal protection material. Nevertheless, the intricate degradation mechanism governing PDMS at ultra-high temperatures remains unclear. Herein, PDMS pyrolysis was in-depth investigated by employing a combination of experimental methodologies and ReaxFF molecular dynamics (ReaxFF-MD) simulations. PDMS model was firstly validated by product distribution analysis and kinetics analysis. Molecular reaction tracking unveils that the pyrolysis pathway primarily is triggered by the cleavage of the Si-C bond, leading to cyclization reactions and fractures within the Si-O framework at elevated temperatures. The pathways leading to the formation of gaseous, liquid, and solid products during thermal cracking are systematically unveiled. Drawing from these insights, DFT calculations reveal Si-C bond dissociation energies (BDEs) of 98.8, 102.2, and 108.2 kcal/mol for Si-CH3, Si-C2H3, and SiC6H5, respectively. MD simulations further indicate that the heightened Si-C BDEs across various silicone rubbers impede their decomposition, thereby augmenting the thermal stability of the material. This study augments our comprehension of the PDMS pyrolysis mechanism and offers theoretical insights for enhancing its thermal stability.