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Estimating the Segregation Strength of Microphase-Separated Diblock Copolymers from the Interfacial Width



Adam B. Burns, Dane Christie, William D. Mulhearn, Richard A. Register


The ever‐growing catalog of monomers being incorporated into block polymers affords exceptional control over phase behavior and nanoscale structure. The segregation strength, χN, is the fundamental link between the molecular‐level detail and the thermodynamics. However, predicting phase behavior mandates at least one experimental measurement of χN for each pair of blocks. This typically requires access to the disordered state. We describe a method for estimating χN from small‐angle X‐ray scattering measurements of the interfacial width between lamellar microdomains, tx, in the microphase‐separated melt. The segregation strength is determined by comparing tx to self‐consistent field theory calculations of the intrinsic interfacial width, ti, as a function of the mean‐field χN. The method is validated using a series of independent experimental measurements of tx and χN, measured via the order‐disorder transition temperature, TODT. The average absolute relative difference between χN calculated from tx and the value calculated from TODT is a modest 11%. Corrections for nonplanarity of the interfaces are investigated but do not improve the agreement between the experiments and theory.
Journal Of Polymer Science


block copolymers, microphase separation, polymer interfaces, self-consistent field theory, small-angle x-ray scattering


Burns, A. , Christie, D. , Mulhearn, W. and Register, R. (2019), Estimating the Segregation Strength of Microphase-Separated Diblock Copolymers from the Interfacial Width, Journal Of Polymer Science, [online], (Accessed May 22, 2024)


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Created June 7, 2019, Updated April 16, 2020