Structure and properties of multilayered siloxane-organic hybrid films prepared using long-chain organotrialkoxysilanes containing CC double bonds

Oriented multilayered films composed of alternating siloxane layers and organic layers were prepared from mixtures of tetramethoxysilane [Si(OMe) ₄] and unsaturated organotrimethoxysilane [RSi(OMe)₃, where R is CH₂CH(CH₂)₈- or CH ₂CH(CH₂)₂CHCH(CH₂)₄-], and the structures and macroscopic properties of the films were studied. Hydrolysis and partial condensation of the precursors led to the formation of amphiphilic organosiloxane species which self-assemble into lamellar phases. Polymerization of the organic phase occurred by UV irradiation, as evidenced by substantial decreases of the IR absorption bands due to -CHCH₂ or -CHCH- groups. The hardness of the films was remarkably increased by the irradiation, due to the covalent linking of adjacent siloxane layers by organic polymerization. The films after organic polymerization had a much higher resistance to an alkaline solution, which enabled the patterning of the films on the micrometer length scale. These results provide an important insight into the structure-property relationships of nanostructured hybrid materials prepared by sol-gel chemistry.