Theoretical Investigation of the Hydrolytic Mechanism of α-Functionalized Alkoxysilanes as Effective Crosslinkers and the Difficulty of Deep Vulcanization in RTV Silicone Rubber

Huihui Xu; Yanhong Gao; Zihou Liu; Yiling Bei

doi:10.3390/ma11091526

Theoretical Investigation of the Hydrolytic Mechanism of α-Functionalized Alkoxysilanes as Effective Crosslinkers and the Difficulty of Deep Vulcanization in RTV Silicone Rubber

Materials (Basel). 2018 Aug 24;11(9):1526. doi: 10.3390/ma11091526.

Authors

Huihui Xu¹, Yanhong Gao², Zihou Liu³, Yiling Bei⁴

Affiliations

¹ Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China. 201411546@mail.sdu.edu.cn.
² Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China. A2936755368@163.com.
³ Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China. EBLX22@163.com.
⁴ Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China. beiyiling@sdu.edu.cn.

Abstract

The reactions between α-, γ-ethylenediaminemethyl trimethyl-ketoxime silane (α-, γ-EAMOS) and H₂O were investigated on the geometries of stationary points, the reaction pathway (IRC), thermodynamic and kinetic analysis by density functional theory (DFT) at the B3LYP/6-311G (d, p) level. Interestingly, the results showed that the hydrolysis activity of α-EAMOS is higher than that of γ-EAMOS, due to the influence of an amino substituent in position α-C on silicon. α-EAMOS can be used as a superior crosslinker for room temperature vulcanized (RTV) silicone rubber to achieve rapid crosslinking without a toxic catalyst. Besides, compared with the reaction between α-EAMOS and H₂O, the reactivity between α-EAMOS and hydroxy siloxane (HO⁻Si(CH₃)₂⁻OSiH₃) was discussed. Particularly, it revealed that the deep vulcanization of RTV silicone rubber is difficult.

Keywords: RTV silicone rubber; ab initio calculation; density functional theory; hydrolytic activity; α-, γ-ethylenediaminemethyl trimethyl-ketoxime silane.