Published Research - Department of Chemistry


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Published in J. AM. CHEM. SOC. 2009, 131, 900–901.


Lamellar structures, consisting of alternating inorganic layers separated by organic moieties, have attracted much attention over a wide range of applications, such as polymer-clay composites, rheology control, and optoelectronic devices. Organosilanes are ideal candidates for such efforts due to their ability to self-assemble and the intrinsic hybrid configuration of organic/inorganic moieties. Yet, the main emphasis has been focused on alkylsilane, where an alkyl group is linked with a silane terminal, i.e., R-SiX3 (R is alkane and X can be halogen or alkoxy). Construction of stacked monolayers of alkylsilane through chemisorption is possible. The demonstrated pathway usually takes place after the monolayer surface is converted to a hydroxylated one. This conversion can be realized by a chemical modification of a nonpolar terminal group to a hydroxyl group. Alternatively, Huo and Parikh found that long-chain alkylsilane could form a lamellar solid or stacked bilayer through solvophobic and van der Waals interactions. Kuroda reported the chain-length dependence study (CnH2n+1Si(OEt)3, n = 12, 14, 16, and 18) of the bilayered structure. Maoz further developed a protocol to grow stacks of bilayers by manipulating the interactions in a stepwise fashion. Collectively, all these studies concluded that the solvophobic and the van der Waals interactions between molecules with long chains were the main driving forces for such a complex assembly. Due to the rather weak interactions between alkylsilanes, the resulting assemblies are usually amorphous and instable at high temperatures; the issue of disturbed packing, as well as difficulties in chemical functionalization of alkyl chains, limits the potential applications for organosilane lamellae.

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