Water Vapor Stability of Silyl Ether Bonds in Silicone Elastomers

Abstract Silyl ether bonds have been frequently noted for their use in vitrimers as dynamic covalent bond sources, but their stability in water-facing situations has been less often noted. We show that polydimethylsiloxane (PDMS) elastomers whose cross-linking junctions are bridged by silyl ether bonds are very stable under exposure to water vapor at elevated temperature, similar to conventional silyl ether-free PDMS. At the same time, they are readily hydrolyzed by hydrochloric acid vapor to decompose and reflow. The study of linear PDMS doped with a silyl ether bond shows that there is minimal hydrolysis after water vapor exposure, but also rapid silyl ether cleavage under exposure to HCl. Comparisons with silyl ester bonds doped in PDMS or siloxane bonds on surfactants highlight that silyl ethers are both highly stable inside an elastomer matrix but can also be much more easily and deliberately decomposed at the end of the life cycle.