n-Alkylsiloxanes:  From Single Monolayers to Layered Crystals. The Formation of Crystalline Polymers from the Hydrolysis ofn-Octadecyltrichlorosilane

Abstract

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.

Designed synthesis of nanostructured siloxane–organic hybrids from amphiphilic silicon-based precursors

“…21,22 This result suggests that the siloxane layers consist of linear (or cyclic) siloxane chains that are partly linked together by additional Si ¶O ¶Si bonds. The steric effects on the condensation of the alkylsilanes to form a bilayer structure have been discussed.…”

“…20 Parikh et al obtained layered alkylsiloxanes by hydrolytic polycondensation of octadecyltrichlorosilane in water. 21 The product was comprised of alternating layers of siloxane networks and bilayer of all-trans alkyl chains covalently attached to the siloxane layers.…”

Ethylene–propylene copolymer/ordered polysilsesquioxane nanocomposites prepared via organic acid‐ or base‐catalyzed binary silica water‐crosslinking reactions

“…Recent much research has shown that 14/28 siloxane-based organic-inorganic hybrid materials prepared by the hydrolysis-condensation of alkoxysilane compounds can be controlled at the nanometer length scale through self-assembly. For instance, the formation of a layer structure composed of alkyl chains with all-trans conformations has been reported for the products obtained by the hydrolytic condensation of alkyltrialkoxysilanes or alkyltrichlorosilanes (12)(13)(14)(15)(16)(17)(18) carbon atoms in the alkyl group) [60][61][62][63][64][65]. Those results are an aid in understanding the formation of the highly-ordered structure in water-crosslinked EPR-g-VTMS/HTMS composites.…”

Preparation of Ionic Polysilsesquioxanes with Regular Structures and Their Ion-Exchange Behaviors

“…For example, it has been reported that trifunctional silane monomers containing long alkyl chains were hydrolyzed to form amphiphilic molecules having silanol groups, resulting in the formation of multilayered PSQs by polycondensation (Scheme 1d) (Parikh et al, 1997;Shimojima et al, 1997). Another method for controlling higher-ordered structures of PSQs is sol-gel reaction (hydrolytic polycondensation) of 1,4-bis(trialkoxysilyl)benzene as a monomer in the presence of surfactants (Inagaki et al, 2002).…”