Butyl Rubber Nanocomposites with Monolayer MoS₂ Additives: Structural Characteristics, Enhanced Mechanical, and Gas...

Emerging two-dimensional (2D) materialsm, such as molybdenum disulfide (MoS₂), offer opportunities to tailor the mechanical and gas barrier properties of polymeric materials. In this study, MoS₂ was exfoliated to monolayers by modification with ethanethiol and nonanethiol. The thicknesses of resulting MoS₂ monolayers were 0.7 nm for MoS₂-ethanethiol and 1.1 nm for MoS₂-nonanethiol. MoS₂ monolayers were added to chlorobutyl rubber to prepare MoS₂-butyl rubber nanocomposites at concentrations of 0.5, 1, 3, and 5 phr. The tensile stress showed a maximum enhancement of about 30.7% for MoS₂-ethanethiol-butyl rubber and 34.8% for MoS₂-nonanethiol-butyl rubber when compared to pure chlorobutyl rubber. In addition, the gas barrier properties were increased by 53.5% in MoS₂-ethanethiol-butyl rubber and 49.6% in MoS₂-nonanethiol-butyl rubber. MoS₂ nanosheets thus enhanced the mechanical and gas barrier properties of chlorobutyl rubber. The nanocomposites that are presented here may be used to manufacture pharmaceutical stoppers with high mechanical and gas barrier properties.