Spin contrast in SANS of polymers in solution

Abstract
We present a small angle neutron scattering study of polymers in solution. The contrast between the scattering lengths of the polymer and the solution is created by dynamic polarization of the nuclei in the sample. We used the spectrometer PAON at G5-3 of the LLB-Saclay- reactor Orphée which is a prototype of a SANS spectrometer using dynamic nuclear polarization. The power of this method can be seen from the results obtained on two different samples: a solution of the homopolymer polystyrene in orthoterphenyl, and a mixture of two homopolymers dissolved in toluene. We observed for the polystyrene sample the decrease in contrast at positive polarization and increase in contrast for negative polarization. For the sample of the polymer mixture in solution we obtained the different structure factors by taking the SANS spectra for different polarizations. The interference term, obtained separately in the same sample, confirms the mutual interaction.