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

Abstract

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 CH₂CH(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.