In situ polymerized ionic liquids in polyester fiber composite membranes for detection of trace oil

In situ trace detection on ultra-clean surfaces is an important technology. The polyester fiber (PF) was introduced to serve as the template, to which the ionic liquids were bonded by hydrogen bonding. Polymerized ionic liquids (PIL) in PF were formed by in situ polymerization with the azodiisobutyronitrile (AIBN) and IL. The trace oil on metal surfaces was enriched by the composite membrane based on similar compatibility principle. The absolute recovery of the trace oil ranged from 91%–99% using this composite membrane. In the extraction samples, desirable linear correlations were obtained for trace oil in the range of 1.25–20 mg/mL. It has been proven that a 1 cm(2) PIL-PF composite membrane can effectively extract as little as 1 mg of lubricating oil on an ultra-clean metal surface of 0.1 m(2) with the LOD of 0.9 mg/mL, making it a promising material for in situ detection of trace oil on metal surfaces.