Tannic acid as a green exfoliating agent: A sustainable pathway towards the development of natural rubber- molybdenum disulfide nanocomposites

Exfoliating agents play a vital role in the dispersion of nanofillers in polymer matrices. The choice of exfoliating agent is a crucial step in the design and synthesis of nanocomposites. The use of bio based exfoliating agents is considered benign for extending the applications of nanocomposites in biomedical systems. The present work discusses the role of a green exfoliating agent, tannic acid (TA), in the formation of natural rubber (NR) - molybdenum disulfide (MoS2) nanocomposites. MoS2 was exfoliated in the absence and presence of tannic acid and the role of the exfoliating agent on the performance of the nanocomposite system was carefully evaluated. The effect of excess exfoliating agent in the system was also monitored by washing out the excess tannic acid and analyzing the properties of nanocomposites. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and thermogravimetric analysis (TGA) were carried out to characterize the TA assisted MoS2 nanosheets. The exfoliated MoS2 (in the absence of TA, excess of TA and after washing out) was then successfully inserted into NR latex and NR-MoS2 nanocomposites were prepared through latex dipping method. In the absence of washing out, the existence of excess tannic acid in the system promoted effective exfoliation leading to enhanced mechanical and thermal properties. However, upon washing out the excess tannic acid, the properties were less than that of the non-washing out system but greater than that of the system devoid of tannic acid. The current study clearly illustrates the dual function of a biomaterial like tannic acid as an exfoliating and reinforcing agent and showcases a green pathway towards the synthesis of natural rubber nanocomposites.

Automated summary

Exfoliating agents are crucial for dispersing nanofillers in polymer matrices. The choice of exfoliating agent is important for designing nanocomposites. The use of bio-based exfoliating agents is considered safe in biomedical systems. This study investigates the role of tannic acid (TA) as a green exfoliating agent in the formation of natural rubber (NR) - molybdenum disulfide (MoS2) nanocomposites. The performance of the nanocomposites was evaluated by exfoliating MoS2 with and without TA, and by washing out the excess TA. The study demonstrates the dual function of TA as an exfoliating and reinforcing agent, and presents a green pathway for synthesizing NR nanocomposites.