Fast electrical response to volatile organic compounds of 2D Au nanoparticle layers embedded into polymers

Abstract

The conductivity of polymer–metal nanocomposites close to the percolation threshold is very sensitive to changes in the metal nanoparticle distances. Here the technical feasibility of a novel type of easy to prepare polymer–metal nanocomposite sensor is explored, which shall be able to detect a unique signal for various volatile organic compounds (VOCs) exhibiting a fast and reversible response. The composite consists of a nearly 2-dimensional Au nanoparticle layer near the percolation threshold thermally embedded into a thermoplastic polymer film. The sensoric response is based on the swelling behavior of the polymeric matrix upon exposure to the organic vapor molecules. Different from conventional nanocomposite sensors that require long-range diffusion of the volatile compound into the bulk of the matrix, the electrical response here only requires the penetration of the VOC a few nanometer below the surface thus causing a rapid detection. The degree of swelling depends on the type of polymer and VOC used as well as on the vapor pressure of the VOC leading to a characteristic response of each polymer to a specific VOC. This enables a “fingerprint” detection of different VOCs by an array of different polymer nanocomposite combined into one sensoric device.