Prepeak
in the structure factor of alcohols is known for a half
century and was attributed to one of two mechanisms (i) self-assembly
in aggregates and (ii) existence of spatial heterogeneity. Although
both explnations are often argued the molecular origin is yet unclear.
In this work, molecular dynamics simulation of neat alcohols and their
mixtures in the presence of an apolar liquid in bulk and in confined
phases is performed to unveil and to clarify the origin of the prepeak
at the molecular scale. Unambiguously, we show that the existence
of the prepeak is the result of the self-assembly in clusters leading
to long-range correlations rather than the spatial heterogeneity.
We also establish that the confinement of neat liquids at the nanoscale
does not erase the clustering and the prepeak but strongly reduce
the spatial heterogeneity. Regarding the binary alcohol/toluene mixtures,
we highlight the possibility to erase the clustering and the spatial
heterogeneity from nanoconfinement inducing the formation of a core–shell
structure. By tuning the interfacial chemistry and pore size, we shed
light on the possibility to control the spatial heterogeneity, the
self-assembly, and the microphase separation.