A molecular simulation study of an organosilane self-assembled monolayer/SiO(2) substrate interface

作者：Yamamoto Hideaki^*; Watanabe Takanobu; Ohdomari Iwao

来源：Journal of Chemical Physics, 2008, 128(16): 164710.

DOI：10.1063/1.2895052

The bonding network of an alkylsilane self-assembled monolayer (SAM)/SiO(2) substrate interface is investigated by means of canonical Monte Carlo (MC) simulations. SAM/SiO(2) systems with different interfacial bonding topologies are sampled by the Metropolis MC method, and the AMBER potential with a newly developed organosilicon parameters are used to obtain an optimized structure with a given bonding topology. The underlying substrates are modeled as hydroxy-terminated (100) or (111) cristobalites. The SAM/SiO(2) interface is characterized by a polysiloxane bonding network which comprises anchoring bonds and cross-linking bonds, namely, molecule-substrate and molecule-molecule Si-O-Si bonds, respectively. We show that at thermal equilibrium, the ratio of the number of anchoring bonds to cross-linking bonds decreases as a total Si-O-Si bond density increases, and that nevertheless, number of anchoring bonds always dominate over that of cross-linking bonds. Moreover we show that the total Si-O-Si bond density strongly affects the lateral ordering of the alkylsilane molecules, and that increase in the Si-O-Si bond density disorders the molecular packing. Our results imply that a lab-to-lab variation in the experimentally prepared SAMs can be attributed to different Si-O-Si bond densities at the SAM/SiO(2) interface.

• 出版日期2008-4-28