Superhydrophobic lignin reinforced rubber film as oil water separator

Natural rubbers (NR) are used widely in industry, yet they exhibit diminished tensile strength and deteriorate under high temperature and moisture conditions. Thus, additional substances are needed to improve their mechanical properties and thermal stability. In this study, we examined a hypothesis that the incorporation of lignin derivative, which was fabricated via aqueous-based copolymerization of kraft lignin (K) and aminopropyl/flurosilsesquioxane (WAPFSS), into the NR matrix would improve the hydrophobic, thermal and mechanical characteristics of NR. The findings of this study revealed that 20 wt% incorporation of lignin-silsesquioxane copolymer (W) into the NR formulation (W20) improved the mechanical properties of NR films by 81 %, which was 58 % higher than its counterpart, i.e., kraft lignin (KL) included NR matrix (K20 sample). Interestingly, the W20 sample was more mechanically durable after heat treatment and water exposure than K20 and pure NR. W20's 150° water contact angle and 10° slide angle confirmed its superhydrophobicity, which survived after high-temperature exposure and sandpaper wear tests. The W20 adsorbed oil at a higher rate than water and showed a 96 % oil separation efficiency. The present study provides foundations for fabricating superhydrophobic and sustainable lignin-reinforced natural rubber films with potential applications as oil and water separators.