ИСТИНА

In the present contribution, the impact of uncharged polymer on the structure the networks formed by entangled wormlike micelles of anionic surfactant was investigated by small-angle neutron scattering (SANS). The scattering behavior of the surfactant component (potassium oleate) was studied upon matching the scattering from the polymer. It was observed that the scattering intensity in the low-Q range varies as Q-1 indicating that the surfactant micelles have a local cylindrical shape. This result was confirmed by cryo-TEM data. To characterize the local structure of these cylindrical objects their cross-sectional radii of gyration Rg and the mass of surfactant per unit length ML were estimated using the Kratky-Porod wormlike chain model approximation. From the radii of gyration Rg the values of the cross-sectional radii of micelles Rc were estimated as Rc = √2Rg. It was shown that both in the absence and in the presence of polymer the cross-sectional radius of wormlike micelles Rc is equal to ca. 20 Å, which is close to the length of the alkyl tail of the surfactant molecule. The scattering from polymer was studied at the solvent composition matching the scattering from the surfactant. It was shown that in the low-Q region, the I(Q) curves in double logarithmic coordinates demonstrate the slope close to -2, which is typical for macromolecules under θ-conditions suggesting that the polymeric chains in polymer-surfactant network have the conformation of a Gaussian coil. Thus, in the prepared polymer-micellar network, the added polymer does not destroy the structure of wormlike surfactant micelles and keeps the Gaussian coil conformation.