  Mixtures of nanoparticles and polymer-like objects are encountered in many
nanotechnological applications and biological systems. We study the behavior of
grafted polymer layers decorated by nanoparticles that are attracted to the
polymers using lattice gas based mean field theory and accompanying
coarse-grained Brownian dynamics simulations. We find that the presence of
nanoparticles can induce large morphological transitions in the layer
morphology. In particular, at moderate nanoparticle concentrations, the
nanoparticles cause a reduction in the height of the polymer layer above the
grafting surface, which occurs via a novel first-order phase transition for
sufficiently strong attraction between the polymers and the nanoparticles and
smoothly for weak attractions. The predictions of the theory qualitatively
agree with the observed behavior of grafted natively unfolded protein strands
upon binding of proteins. The results also inform ways of designing nanopolymer
layer morphologies.
