Nature of Viscoelasticity in Lamellar Block Copolymers: Contraction Correlated to Strain Localization

We determined the local strain profile in sheared lamellar block copolymers. A trilayer model, based on elastic brushes separated by viscous interpenetration zones, captures the rheological response of these materials and provides a measure of the relative contributions of elastic versus viscous strain. The elastic chain distortions were evident from a reversible lamellar contraction, as measured from in situ small-angle x-ray scattering. The contraction was directly correlated to the elastic strain from our trilayer model; three distinct diblock copolymers conform to the predicted relationship, thus suggesting universal behavior. Comments Copyright American Physical Society. Reprinted from Physical Review Letters, Volume 83, Issue 14, October 1999, pages 2861-2864. Publisher URL: http://dx.doi.org/10.1103/PhysRevLett.83.2861 This journal article is available at ScholarlyCommons: http://repository.upenn.edu/mse_papers/88 VOLUME 83, NUMBER 14 P H Y S I C A L R E V I E W L E T T E R S 4 OCTOBER 1999 Nature of Viscoelasticity in Lamellar Block Copolymers: Contraction Correlated to Strain Localization D. L. Polis and K. I. Winey* Laboratory for Research on the Structure of Matter, Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6272