Structural changes of poly(N-isopropylacrylamide)-based microgels induced by hydrostatic pressure and temperature studied by small angle neutron scattering

We study the structural properties of microgels made of poly(N-isopropylacrylamide) and acrylic acid as a function of hydrostatic pressure and temperature using small angle neutron scattering. Hydrostatic pressure induces particle deswelling by changing the mixing of the microgel with the solvent, similar to temperature. We extend this analogy to the structural properties of the particles and show that the form factor at a certain temperature is equal to the form factor at a certain hydrostatic pressure. We fit the results with an existent model for the microgel structure and carefully analyze the fitting procedure in order to obtain physically meaningful values of the free parameters in the model. (C) 2010 American Institute of Physics. [doi:10.1063/1.3447386]