International audienceThe confinement of fluids in channels of nanometer size presents unprecedented opportunities to reveal emergent physicochemical properties that have no equivalent in the corresponding bulk system. We present an experimental study of fully miscible binary low-molecular weight liquids confined in nanopores. Under these conditions, the mixtures form a microphase-separated state with two regions of different compositions forming the core and the shell of a concentric tubular nanostructure. We combine neutron diffraction and DSC measurements to assess the thermal behavior of this unusual phase. These results show that crystallization is suppressed, leading to glassy behaviors characterized by anomalies in the density and the heat capacity. We reveal the coexistence of two different glass transitions, providing the direct proof for two different enthalpic relaxation times. It leads to the conclusion that the subcomponents of the microphase-separated mixture each obey distinct dynamical behaviors. This phenomenon is all the more unusual considering that the thicknesses of the core and the shell are only one to three molecular sizes. These results have important implications for processes involving interfacial multicomponents fluids, including heterogeneous catalysis, microfluidic devices, nanofiltration or oil industry
Binary liquid mixtures can exhibit nanosegregation, albeit being fully miscible and homogeneous at the macroscopic scale. This tendency can be amplified by geometrical nanoconfinement, leading to remarkable properties. This work investigates the molecular dynamics of tert-Butanol (TBA)-Toluene (TOL) mixtures confined in silica nanochannels by quasielastic neutron scattering and molecular dynamics simulation. It reveals a decoupling of the molecular motion of each constituent of the binary liquid, which can be followed independently by selective isotopic HD labelling. We argue that this behavior is the signature of spatially
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