Combined neutron reflectometry and rheology

We have combined neutron reflectometry with rheology in order to investigate the solid boundary of liquids and polymers under shear deformation. Our approach allows one to apply a controlled stress to a material while resolving the structural arrange-ments on the sub nanometer length scale with neutron reflectivity, off-specular and small angle scattering at the same time. The specularly reflected neutron intensity of a 20 % by weight solution of the Pluronic F127 in deuterated water in contact to a OTS covered and a Piranha treated silicon wafer is evaluated. We find a pronounced difference in the structure formed by the polymer micelles at the two surfaces, which is explained by the difference in the affinity of the micellar shell to the solid interfaces. Under deformation the near interface structure changes at deformations of about 2, 30 and 900 %. The structural changes are correlated with changes in the storage and loss modulus of the polymer solution revealing a transition from more solid to more liquid like properties