Small angle neutron scattering (SANS) studies of a conjugated polyelectrolyte in aqueous solution

Small angle neutron scattering (SANS) by the conjugated polyelectrolyte, poly[5-methoxy-2-(4-sulfobutoxy)-1,4-phenylene-vinylene], was studied in semi-dilute solutions. A broad peak appears at high momentum transfer (q) for all concentrations. The peak position (q(m)) and intensity (I(q(m))) scale with polymer concentration as q(m) similar to c(1/2) and I(q(m))/c similar to c(-1/2), consistent with polyelectrolyte theory. The upturn of I(q) at q < 0.08 (-1) indicates chain aggregation. Addition of excess salt removes the broad peak from I(q). In high-salt solutions, I(q) similar to q(-1) implying a rod-like conformation with a persistence length larger than 800 Angstrom. (C) 2001 Elsevier Science B.V. All rights reserved.