Probing monolayer stability via deterioration of functionalized porous silicon in alkaline environments

CHED 478

Wassim W. Labaki, porterl@wabash.edu and Lon A. Porter Jr. Department of Chemistry, Wabash College, Crawfordsville, IN 47933
Porous silicon (por-Si), a unique nanocrystalline form of silicon, has demonstrated great potential for a variety of applications. However, hydride-terminated por-Si is easily oxidized to silicon dioxide and dissolved under alkaline conditions. Using thermal assisted, Lewis acid catalyzed, and carbocation mediated hydrosilylation methods, we have functionalized por-Si surfaces with alkyl monolayers. Transmission FTIR spectroscopy indicates that the functionalization of the por-Si surface provides greatly-improved stability for an extended period of time in alkaline environments (aqueous, pH 12-14). In each of the three reactions presented, the stability of the alkyl-functionalized por-Si surface was greatly improved when compared to the unfunctionalized control sample. The functionalized samples oxidized and dissolved at a greatly reduced rate when compared to the deterioration rate of the silicon-hydride control sample. Based on these initial results, the thermal reaction appears to give the greatest enhancement of stability.