  Monolayers of soft colloidal particles confined at fluid interfaces have been
attracting increasing interest for fundamental studies and applications alike.
However, establishing the relation between their internal architecture, which
is controlled during synthesis, and their structural and mechanical properties
upon interfacial confinement, which define the monolayer's properties, remains
an elusive task. Here, we propose a comprehensive study elucidating this
relation for a system of microgels with tunable architecture. We synthesize
core-shell microgels, whose soft core can be chemically degraded in a
controlled fashion, yielding particles ranging from analogues of standard
batch-synthesized to completely hollow microgels after total core removal. We
characterize the internal structure of these particles, their swelling
properties in bulk and their morphologies upon adsorption at an oil-water
interface via a combination of numerical simulations and complementary
experiments. In particular, we confirm that hollow microgels are mechanically
stable in bulk aqueous conditions and that the progressive removal of the core
leads to a significant flattening of the microgels, which become disk-like
particles, at the interface. At low compression, the mechanical response of the
monolayer is dominated by the presence of loosely crosslinked polymers forming
a corona surrounding the particle within the interfacial plane, regardless of
the presence of a core. By contrast, at high compression, the absence of a core
enables the particles to deform in the direction orthogonal to the interface.
These findings shed new light on which structural features of soft particles
determine their interfacial behaviour, enabling new design strategies for
tailored materials.
