Influence of thiol groups on the ethylene adsorption and conductivity properties of the modified porous clay heterostructures (PCHS) using as ethylene scavenger in smart packaging

Porous Clay Heterostructures (PCHs) were prepared by the surfactant-directed assembly of silica source (tetraethylorthosilicate-TEOS) and sodium-bentonite (Na-BTN) clay. These PCHs were subsequently modified to an organic-inorganic hybrid material by the co-condensation reaction of TEOS with (3-mercaptopropyl trimethoxy silane (MPTMS) in 1:1, 2:1, and 4:1 molar ratios of MPTMS to TEOS to obtain conductive porous clays, here referred to as modified MPPCHs. Various weight percentage of MPPCHs at 1, 3, and 5 wt% were blended with polypropylene (PP) and fabricated into the PP/modified MPPCHs nanocomposite films. Analysis revealed that the surface areas of modified MPPCHs increased significantly from Na-BTN; however, the higher MPTMS contents resulted in less porous surface areas. An ethylene adsorption study showed that modified MPPCHs exhibited higher adsorption efficiency of ethylene gas than that of Na-BTN due to the non-polar property of the modified functional groups. Subsequently, the electrical conductivity of the modified MPPCHs with various contents of thiol group was investigated to evaluate potential use in ethylene scavenger/sensor applications.