Surface-grafting modification of attapulgite nanorods with polysiloxane coupling agents for highly-efficient mechanical and triboelectric performance enhancement of silicone rubbers

The quest for polymeric materials that combine mechanical robustness with high triboelectric charge density is paramount in a novel kind of triboelectric nanogenerators (TENGs) that can directly convert mechanical energy into electricity in a clean and green way. Silicone rubbers (SRs) are one of the most frequently-used triboelectric materials owing to their excellent processability and high tendency of being negatively charged via contact electrification (CE), but their potential can be further maximized by strategic doping with nanomaterials. Herein, we introduced a novel kind of naturally occurring clay mineral attapulgite nanorods with surfaces modified by elaborately-synthesized polysiloxane coupling agents (PCA@ATP) to elevate the mechanical and triboelectric performance of silicone rubbers (SRs) efficiently. The modified SRs not only amplified the tensile strength by over 21 % with the addition of only 4 phr PCA@ATP, but also possessed a significant increase by 40.11 % in triboelectric charge density (ρ(Q)). Moreover, the ρ(Q) of modified SR films showed a continuously increasing trend with a further increase of PCA@ATP content. Particularly, SR films doped with 8 phr PCA@ATP showcased a ρ(Q) enhancement by 59 %, rendering them as exceptional candidates for TENGs. Through rigorous experimentation, we observed that increasing the impact frequency and PCA@ATP content consistently enhanced both the output voltage and current of the SR-based TENGs. In comparison to undoped SR films, doping with 4 phr and 8 phr PCA@ATP resulted in an impressive 122 % and 146.68 % boost in voltage and a 393 % and 508.53 % surge in power, respectively. This highly-efficient mechanical and triboelectric performance enhancement of SRs can be ascribed to the homogeneous incorporation of 1D inorganic nanomaterials PCA@ATPs with high Young's modulus, dielectric constant, and topologically-reinforced interface, leading to a comprehensive improvement of mechanical energy transfer, conversion, storage, and dissipation efficiency. This study presents a pioneering strategy for crafting robust triboelectric materials with superior CE performance, paving the way for more effective mechanical energy harvesting.