Macromolecules, Vol.30, No.20, 6376-6384, 1997
Microscopic Theory for the Lozenge Contour Plots in Scattering from Stretched Polymer Networks
We present a consistent explanation for the appearance of "lozenge" shapes in contour plots of the two-dimensional scattering intensity from stretched polymer networks. We show that lozenge patterns arise as a result of chain material that is not directly deformed by the stretch. This accounts for the lozenges which appear in scattering from pure polymer networks with some labeled chains, which we show explicitly by taking the model of a labeled chain whose midsection is confined to a stretched tube but whose ends are unconstrained. The model produces excellent fits to data. We discuss qualitatively the lozenges which are a precursor to "butterfly" patterns in scattering from networks containing a mobile labeled component. We also show that lozenges cannot consistently be explained by coupling tube constraints to the stretch alone.
Keywords:ANGLE NEUTRON-SCATTERING;TOPOLOGICAL CONSTRAINTS;SANS INVESTIGATIONS;FREE CHAINS;MELTS;RELAXATION;FLUCTUATIONS