Sodium alginate-assisted exfoliation of MoS2 and its reinforcement in polymer nanocomposites

•SA-MoS2 nanosheets were prepared by exfoliation of MoS2 with assistance of SA.•All the materials were biodegradable and without any organic solvent added.•SA-MoS2 nanosheets were successfully functionalized during the exfoliated.•SA-MoS2 nanosheets improved thermal and mechanical properties of polymers greatly.

In this work, molybdenum disulfide (MoS2) nanosheets were facilely prepared by direct exfoliation of MoS2 in aqueous media with the assistance of sodium alginate (SA). Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectra results showed that the raw MoS2 was successfully exfoliated into few-layer MoS2 nanosheets (SA-MoS2). FTIR and thermal gravimetric analysis (TGA) investigations showed that the obtained MoS2 nanosheets were modified by SA after exfoliation and improved dispersion in water were achieved. The obtained SA-MoS2 nanosheets were employed to reinforce the water-soluble polymer SA. No obvious macroscopic phase separation could be found from the SA/SA-MoS2 films. Dynamic mechanical analysis (DMA) results showed that almost 9 times enhancement for the storage modulus of SA was achieved with the incorporation of only 0.5 wt% of SA-MoS2, and the thermal stability of SA was also found improved with the addition of SA-MoS2 according to the thermal gravimetric analysis TGA results.