The influence of MoS₂/carbon dots hybrid particles on mechanical properties of natural rubber latex

Molybdenum disulfide(MoS₂) has a special structure and excellent mechanical properties, making it a promising reinforcing filler for polymers. Carbon dots (CDs) have good antioxidant properties, and the addition of CDs during the synthesis of MoS₂ can affect its morphology and size. In this work, a new one-step hydrothermal synthesis process was employed to prepare CDs/MoS₂ hybrid particles. Thiourea, sodium molybdate, and glucose were employed as sources of sulfur, molybdenum, and carbon, respectively. The structure and morphology of MoS₂ and CDs/MoS₂ were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), mapping surface scanning (SEM–EDS), and Fourier transform infrared spectroscopy (FTIR). The results show that the prepared 2H-MoS₂ is stacked into flower-like spheres with size around 2–10 μm; with the formation of CDs, the size of MoS₂ rapidly decreases to less than 1 μm and the CDs are evenly distributed on its surface with mass ratio of 40.2% (CDs in CDs/MoS₂). Subsequently, the CDs/MoS₂ were used as reinforcing fillers for natural rubber (NR) latex. The results of mechanical properties show that tear strength, tensile strength, modulus, and elongation at break are increased by the addition of CDs/MoS₂ in a very lower loading, and the maximum increment ratio is 45.6% and 12.1% when compared to NR-0; the dynamic mechanical analysis and cross-link density results indicated that the CDs/MoS₂ can simultaneously improve rigidity and elasticity of NR. The thermal stability results suggest that the CDs/MoS₂ shows positive effects on thermal stability of NR.