This is a research program designed to study polymer blends and polymer networks by scattering methods. The main experimental thrust will continue to be small-angle neutron scattering (SANS), and will be extended to include comparative and complementary small-angle x-ray (SAXS) measurements. The polymer blends will be studied by SANS and SAXS, and both equilibrium properties and polymer interdiffusion are to be investigated. Polymer networks in bulk and in the swollen state will be studied by SANS only. Concurrently, elastic recoil scattering (ERD) will be exploited for the measurement of polymer interdiffusion and solvent diffusion in bulk polymers. Preliminary SAXS measurements and all ERD measurements will be performed at the University of Michigan. SAXS measurements requiring high resolution and high intensity will be carried out at Brookhaven or Standford. Most SANS experiments are planned to be executed at Oak Ridge but some may be undertaken at the University of Missouri or at Argonne. All three scattering methods SANS, SAXS, and ERD are particularly important in the measurement of small diffusion constants of the order of 10-14 cm2/sec and less. An important part of the ERD study will be to improve instrumental resolution and to provide a low temperature central system needed for the solvent diffusion studies.