Polymer-silica hybrids: Evaluation of grafted poly(acrylonitrile) as organic phase for high-performance liquid chromatography

Poly(acrylonitrile) with a terminal reactive group at one side of the main chain was prepared by telomerization of acrylonitrile with 3-mercaptopropyltrimethoxysilane and then immobilized onto porous silica. HPLC using the packed column (SI-AN(n)) and an aqueous solution as a mobile phase showed several unique retention behaviors for hydrocarbons: (1) the retention factor for alkylbenzenes was almost independent of the alkyl length although simply cyanopropylated silica (Sil-CN) showed the increase of the retention time with increase of the alkyl length. (2) Sil-AN(n) showed remarkably better selectivity for pi-electron containing hydrocarbons compared with Sil-CN and hydrophobized silica. In this paper, such specificity of Sil-AN(n) is discussed in relation to pi-electron recognition ability of poly(acrylonitrile) moiety.