Small-angle neutron scattering interface effects

Several methods can be used to determine the fraction of segments, (p), of the polymer chain actually in contact with the surface. Small-angle neutron scattering (SANS) and neutron reflectivity (NR) ellipsometry, electron paramagnetic resonance (EPR), IR, and NMR spectroscopy have all been used. Most suffer from the drawback that the distinction between bound and free segments close to the interface is often difficult to define. This distinction is important as the bound fraction effectively determines how well anchored the polymer is to the surface. 

---