Lower Limit of Interfacial Thermal Resistance across the Interface between an Imidazolium Ionic Liquid and Solid Surface

Abstract

Understanding of energy transport across the solid–liquid interface is essential for the rational design of efficient heat dissipation capabilities. In this work, we show that the molecular orientation of liquid near the solid surface dominates the thermal transport across the imidazolium ionic liquids (IL)/graphene interface via molecular dynamics simulations. The molecular orientation is defined as the parallelism between the imidazole ring in IL and graphene and is controlled by wettability of graphene. Interfacial thermal resistance (ITR) will decrease linearly with the parallelism, which is suitable for IL with different tail chain length (2, 4, 6, and 8). From the linear relationship, a lower limit of ITR for the IL–graphene interface can be predicted, which is on the order of ∼6 m2 K/GW and stands for the lower bound of ITR across the solid–liquid interface. Furthermore, it is indicated that the parallel imidazole ring in IL facilitates the thermal transport via shifting the dominating vibrational modes to a higher frequency (∼15 THz). These findings show that the molecular orientation can be an effective factor to control the interfacial thermal transport, which can shed light on the future rational designs of some key chemical engineering processes, such as IL-based coolants, batteries, nanoelectrical devices, and so on.

Understanding Electric Field‐Dependent Structure Variation of Functional Ionic Liquids at the Electrode Interface

“…To describe the ordering and distribution of ions at the interface, the mean orientation distribution (P) of the imidazole ring and [OTf] À in ILs is calculated as follows [Eq. (1)]: [29]…”

“…As the distance from metal surface increases, the configuration of imidazole ring and anion will transform from parallel case (d < 4 Å) to vertical case (4 < d < 7 Å), and finally to the random distribution (d > 10 Å), demonstrating the layered structures reported by the previous works. [29] To measure the influence of alkyl chain length and sulfonic group on the average orientation P ave systematically, all the results of P ave for different ILs were summarized in Figure 4. The P ave of ring and anion in bulk C N mimOTf at the different electrical fields are close to 0.0 (Figure 4a-b), meaning that the ILs distributes randomly and the E is smaller than the inner electrical field between cation and anion.…”

“…al showed that the extra charge of electrodes can induce the formation of highly ordered interfacial ILs structure and enhance the thermal transport efficiency across solid-ILs interface. [29][30] Mao et al demonstrated that the surface-active ILs could induce the obvious interfacial self-assembly and form the polar/non-polar regions, which could increase the energy density of supercapacitor greatly. [23] Martin Z. developed a simple theory of solvent-free ionic liquids to describe both overscreening and crowding phenomena in ILs, and found that overscreening is pronounced at small voltages and gradually replaced by the formation of electric double layer at large voltages.…”

Theoretical Insights Into the Depolymerization Mechanism of Lignin to Methyl p-hydroxycinnamate by [Bmim][FeCl4] Ionic Liquid

“…Further, we investigated the reaction mechanism of the cleavage of β-O-4 bond in GG to guaiacol by -SO 3 H functionalized ILs (Zhang et al, 2019). Given the versatility of IL catalysts (He et al, 2015; Wang et al, 2015; Meng et al, 2017; Qian et al, 2018; Zhang et al, 2018) and our keen interest in the research of biomass (Cai et al, 2015; Suresh et al, 2017), an elegant approach for catalytic transform of lignin to structurally defined aromatic esters is put forward here. According to Otera (1993) and Hoydonckx et al (2004), the lignin model compound, phenyl p-hydroxycinnamate ( PPC ), was used to produce MPC by cleavage of the γ-O ester linkage using MBIL [Bmim][FeCl 4 ] as catalyst (Scheme 2).…”

Dynamic control of heat flow using a spin-chain ladder cuprate film and an ionic liquid

“…First, G g/Au was determined to be ~ 50 MW/(m 2 K) using data at f > 10 5 Hz, where the value seems plausible, referring to a previous report 32 . Then, G Au/IL was fixed at 50 MW/(m 2 K) because G Au/IL is presumed to be > 10 MW/(m 2 ·K) 33 , 34 , and we found that the contribution of G Au/IL to the phase lag at f ~ 10 4 –10 5 Hz is negligible when G Au/IL > 10 MW/(m 2 K). Finally, d IL and G LCCO for A were determined to be ~ 700 nm and 4 MW/(m 2 K), respectively, by analytical fitting.…”