The nanotechnology shift from static toward stimuli-responsive
systems is gaining momentum. We study adaptive and responsive Langmuir
films at the air/water interface to facilitate the creation of two-dimensional
(2D) complex systems. We verify the possibility of controlling the
assembly of relatively large entities,i.e., nanoparticles
with diameter around 90 nm, by inducing conformational changes within
an about 5 nm poly(N-isopropyl acrylamide) (PNIPAM)
capping layer. The system performs reversible switching between uniform
and nonuniform states. The densely packed and uniform state is observed
at a higher temperature,i.e., opposite to most phase
transitions, where more ordered phases appear at lower temperatures.
The induced nanoparticles’ conformational changes result in
different properties of the interfacial monolayer, including various
types of aggregation. The analysis of surface pressure at different
temperatures and upon temperature changes, surface potential measurements,
surface rheology experiments, Brewster angle microscopy (BAM), and
scanning electron microscopy (SEM) observations are accompanied by
calculations to discuss the principles of the nanoparticles’
self-assembly. Those findings provide guidelines for designing other
adaptive 2D systems, such as programable membranes or optical interfacial
devices.