Introduction of amino groups into the interlayer space of graphite oxide using 3-aminopropylethoxysilanes

Graphite oxide was silylated by 3-aminopropylethoxysilanes under various reaction conditions. Two types of layered materials were obtained when 3-aminopropyltriethoxysilane was reacted with graphite oxide. One obtained at lower temperatures was 3-aminopropyltriethoxysilane-intercalated graphite oxide with an interlayer spacing of 1.27 nm, in which amino groups of 3-aminopropyltriethoxysilane were bonded to hydroxyl groups of graphite oxide. At higher temperatures, silylation of graphite oxide occurred, giving a phase with larger interlayer spacing of 1.37 nm. Chemical reduction of graphite oxide to disordered carbon by amino groups occurred at the same time. Similar reactions occurred when 3-aminopropyldiethoxymethylsilane and 3-aminopropylethoxydimethylsilane were reacted and they were introduced into the interlayer space of graphite oxide. Large amounts of silicon, and accordingly amino groups, were introduced in graphite oxide when it was silylated by 3-aminopropyldiethoxymethylsilane because its reactivity for chemical reduction of graphite oxide was relatively lower than that of 3-aminopropyltriethoxysilane and additional silylation was possible. The amount of amino groups available for chemical adsorption of formaldehyde reached a very high value of 3.8 mmol/g for graphite oxide silylated by 3-aminopropyldiethoxymethylsilane.