Recognizing the function of different silane coupling agents on MXene adsorption/barrier behavior in solvent-borne epoxy coatings: Experimental studies, density functional theory, and molecular dynamics simulations
Sepideh Pourhashem, Mohammad Hassan Hadizadeh, Xiaohong Ji, Ziyang Zhou, Jizhou Duan, Xiaohong Ci, Hao Lu, Baorong Hou
Abstract
Two different silane agents including 3-aminopropyltriethoxysiane and tetraethyl orthosilicate are used to achieve MXene nanosheets grafted with amino-silane (Silane@MXene) and MXene nanosheets covered with SiO 2 nanoparticles (SiO 2 @MXene), respectively. The Silane@MXene and SiO 2 @MXene are used as nanofillers in a solvent-based epoxy coating and applied with a dry film thickness of 200 ± 50 μm on steel substrates. The neat epoxy and epoxy loaded with SiO 2 @MXene and Silane@MXene show water contact angles of 75.8°, 88.4°, and 115.8° and adhesion strengths of 3.2, 4.8, and 6 MPa, respectively. The neat sample fails after 28 days of immersion in the 3.5 wt% NaCl solution, while the coatings loaded with SiO 2 @MXene and Silane@MXene show low frequency impedance modulus of 4.34 × 10 7 and 2.97 × 10 8 Ω.cm 2 after 56 days of immersion, respectively. Moreover, density functional theory calculations indicate that both APTES and TEOS structures exhibit reactivity and promise for interacting with the MXene/solution interface. Molecular dynamics simulation shows that both Silane@MXene and SiO 2 @MXene are effective in protecting against the 3.5 wt% NaCl solution. The diffusion of Na + and Cl − in Silane@MXene is marginally higher compared to the SiO 2 @MXene systems. The exceptional adsorption capacity of the Silane@MXene makes it a suitable material for protection against NaCl solution.