n-alkylsiloxanes: From single monolayers to layered crystals. The formation of crystalline polymers from the hydrolysis of n-octadecyltrichlorosilane


Atul N. Parikh, Meredith A. Schivley, Eunhae Koo, Kannan Seshadri, David Aurentz, Karl Mueller, and David L. Allara, Journal of the American Chemical Society 119, 3135 (1997)

Formation of a new class of layered, microcrystalline polymers from a simple hydrolytic polycondensation of n-alkyltrichlorosilanes in water is demonstrated. The structure of the polymeric condensate, determined from a combination of spectroscopic, diffraction, and thermal analysis techniques, consists of highly uniform, pillared microcrystallites in which the inorganic siloxy backbones are present in periodic layers, each containing a monomolecular layer of intercalated water, separated by crystalline assemblies of alkyl chains. The alkyl-chain organization shows a remarkable resemblance to that in highly organized, self-assembled monolayers formed from the precursor silane molecules on hydrophilic substrates and this parallel lends support to the critical importance of water in monolayer self-assembly of silanes.