Thermodynamics of Symmetric Diblock Copolymers Containing Poly(styrene-ran-styrenesulfonic acid)

Abstract

<p>We examine the thermodynamic behavior of diblock copolymers representing the binary pairs of the ternary system: poly(dimethylsiloxane)/poly(ethylene<em>-stat</em>-propylene)/poly(styrene-<em>ran</em>-styrenesulfonic acid), <em>D</em>/<em>E</em><em>P</em>/<em>S</em><em>S</em>. We employ small-angle X-ray scattering, electron microscopy, and rheology to characterize the order-to-disorder transition temperature <em>T</em>ODTand lamellar period <em>d</em> of 28 materials with varying molecular weights and sulfonation extents. These data are then interpreted in the context of self-consistent mean-field theory employing the continuous Gaussian chain model to deduce the interaction parameters as a function of temperature and sulfonation extent. We find that while <em>E</em><em>P</em><em>D</em> and <em>S</em><em>S</em><em>E</em><em>P</em> are amenable to such treatment, the <em>S</em><em>S</em>/<em>D</em> interaction forces <em>S</em><em>S</em><em>D</em> chains to stretch beyond the realm of applicability of the Gaussian chain model.</p>