Internal mass segregation in PNIPAM hydrogels

Colloidal hydrogels swell and deswell depending on the environmental conditions. These size changes imply changes in the single-particle properties, including their internal structure, which can result in non-trivial morphologies. Here, we use PNIPAM-AAc ultra-low crosslinked particles at different temperature and charge, together with light and neutron scattering, to find that the particles are not homogenous. Instead, they are remarkably heterogeneous. We interpret the results in terms of phase separation using the Borue and Erukhimovich theory.