Abstract
This work presents theoretical studies of the interaction of molecules of several gaseous pollutants with polyacrylonitrile (PAN) surface in the presence of a water and/or oxygen molecule. For this purpose, a PAN cluster model has been proposed by the methods of quantum chemical calculations and molecular modeling. The energy-favorable positions, in which the gas molecules are located relative to the surface of the PAN cluster, are determined and the thermodynamic and the following geometric parameters of the systems are calculated: “PAN cluster − oxygen molecule”, “PAN cluster − oxygen molecule − gas molecule”, “PAN cluster − water molecule − molecule of oxygen”, and “PAN cluster − a molecule of water − an oxygen molecule − a gas molecule”. It is concluded that PAN in atmospheric air in the presence of oxygen molecules is sensitive to carbon oxide (IV), sulfur (IV) oxide, chlorine, hydrogen sulfide and carbon oxide (II). In an anoxic environment, PAN films will show selective sensitivity to chlorine. The presence of water molecules in the investigated air should not affect the gas sensitivity of PAN films.
Highlights
It is known that polyacrylonitrile (PAN) under the influence of thermal heating can gradually change its structure [1,2,3,4]
Pentamers, arranged one above the other cluster consisting of two macromolecules, PAN pentamers, arranged one above theprogram other was obtained obtained by the method of quantum chemical calculations in the HyperChem using the by the methodquantum of quantum chemical calculations in the HyperChem using the semiempirical semiempirical chemical calculation scheme
The middle of the PAN cluster is energetically favorable. This indicates a physical adsorption of the cluster − oxygen molecule − gas molecule” system are presented in Table 1 and Figure 3
Summary
It is known that polyacrylonitrile (PAN) under the influence of thermal heating can gradually change its structure [1,2,3,4]. Thin films of PAN that have passed infrared (IR) annealing at temperatures of 300–600 ◦ C have semiconductor and gas sensitive properties already at room temperature [5,7,8,9,10,11,12,13]. Such materials can be used in energy-efficient gas sensors to monitor air quality [10,11]. The mechanism of interaction of molecules of simple gases with the surface of PAN was investigated using quantum chemical calculations. The authors noted that on the surface of a single-layer cluster of PAN, molecules of gases are adsorbed by the mechanism of chemical adsorption. It was shown that a physical adsorption of simple gas molecules can occur on a two-layer PAN cluster [16]
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