Theory of Microphase Segregation in ABA Triblock Comb-Shaped Copolymers: Lamellar Mesophase

Abstract

A theory describing lamellar mesophases formed in the melt of ABA triblock copolymers with strongly incompatible comblike blocks is developed using a combination of a strong-stretching self-consistent field (SS-SCF) analytical approach and numerical self-consistent field calculations based on the Scheutjens-Fleer (SF-SCF) methods. The structural and thermodynamic properties of the lamellae are analyzed as a function of their architectural parameters, i.e., grafting density and polymerization degree of the main and side chains in the comb-shaped blocks. In particular, we distinguish between the loops and bridges formed by the middle comb-shaped block and demonstrate how a fraction of the bridges connecting the neighboring AB interfaces of the lamellar layers and shear modulus of the mesophase are mediated by the architectural parameters of the comblike blocks. In particular, we predict an increase in the shear modulus upon replacement of the linear ABA triblock copolymers by comblike ones with the same composition. The asymptotic analytical predictions of the theory are complemented by the results of numerical modeling.