  Simulations of the effects of stellar fly-bys on planetary systems in
star-forming regions show a strong dependence on subtle variations in the
initial spatial and kinematic substructure of the regions. For similar stellar
densities, the more substructured star-forming regions disrupt up to a factor
of two more planetary systems. We extend this work to look at the effects of
substructure on stellar binary populations. We present $N$-body simulations of
substructured, and non-substructured (smooth) star-forming regions in which we
place different populations of stellar binaries. We find that for binary
populations that are dominated by close ($<$100au) systems, a higher proportion
are destroyed in substructured regions. However, for wider systems ($>$100au),
a higher proportion are destroyed in smooth regions. The difference is likely
due to the hard-soft, or fast-slow boundary for binary destruction. Hard
(fast/close) binaries are more likely to be destroyed in environments with a
small velocity dispersion (kinematically substructured regions), whereas soft
(slow/wide) binaries are more likely to be destroyed in environments with
higher velocity dispersions (non-kinematically substructured regions). Due to
the vast range of stellar binary semimajor axes in star-forming regions
($10^{-2} - 10^4$au) these differences are small and hence unlikely to be
observable. However, planetary systems have a much smaller initial semimajor
axis range (likely $\sim$1 -- 100au for gas giants) and here the difference in
the fraction of companions due to substructure could be observed if the
star-forming regions that disrupt planetary systems formed with similar stellar
densities.
