Nanoconfined liquid aliphatic compounds under external electric fields: roles of headgroup and alkyl chain length

Understanding the structures and dynamics of the confined liquids in nonequilibrium states becomes increasingly important for many practical applications, e.g., nanolubrication and micro/nanofabrication. In the present paper, the effect of external electric fields (EEFs) on several normal straight-chain aliphatic liquids nanoconfined in a ball-plate configuration has been investigated by measuring the dynamic film thickness with the thin film interferometry and calculating the effective viscosity. The results indicate that the EEF effect on promoting the formation of interfacial ordered regions due to dipole orientation and hence affecting the effective viscosity of the confined liquid film is dependent on the type of the headgroup of the molecule. The dipole orientation in the n-alkanol film with a shorter alkyl chain has a larger probability to be affected by EEFs due to the smaller dispersion force and the larger ionic concentration.

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