In this work, we demonstrate a conjugated polymer mesh as oil absorbent capable of in situ self-regeneration via wettability switch during electrochemical oxidation and reduction. We fabricate the absorbent through electropolymerization of polypyrrole-dodecylbenzenesulfonate (PPy(DBS)) on the surfaces of carbon nanotubes (CNTs) grown out of the surface of a stainless steel (SS) mesh. The PPy(DBS)-coated mesh shows oleophilic property when electrochemically oxidized, allowing the mesh to absorb oils (i.e., oils stick to the polymer surface; oils are trapped within the micro-pores of mesh). Under reduction, the surface switches to oleophobic (i.e., oils do not stick to the polymer surface), which allows trapped-oils by the mesh to be released, while in situ self-regenerating the polymer surface. We also observe that this switchable adhesion property is further enhanced incorporating CNTs into the structure. Using this approach, in situ absorbing and releasing of dichloromethane (DCM) in aqueous solution is demonstrated using a rolled-up absorbent mesh. We further demonstrate the wettability switch performance (characterizing the retention force when oxidized and switch time when reduced) of the absorbent during 250 redox cycles. In addition, the potential usage of this oil absorbent for oil/water separation is demonstrated by transporting DCM from one vial to another. Together, this novel adsorbent shows great promise towards high-efficient continuous oil/water separation applications.
[1] J. Ge, H. Zhao, H. Zhu, J. Huang, L. Shi, and S. Yu, “Advanced sorbents for oil-spill cleanup: recent advances and future perspectives,” Advanced Materials, 28 (47), 10459–10490, (2016).
[2] Z. Chu, Y. Feng, and S. Seeger, “Oil/water separation with selective superantiwetting/superwetting surface materials,” Angewandte Chemie - International Edition, 54 (8), 2328–2338, (2015).