title: Dual modes of self-assembly in superstrongly segregated bicomponent triblock copolymer melts.
abstract: While ABC triblock copolymers are known to form a plethora of dual-mode (i.e., order-on-order) nanostructures, bicomponent ABA triblock copolymers normally self-assemble into single morphologies at thermodynamic incompatibility levels up to the strong-segregation regime. In this study, we employ on-lattice Monte Carlo simulations to examine the phase behavior of molecularly asymmetric A(1)BA(2) copolymers possessing chemically identical endblocks differing significantly in length. In the limit of superstrong segregation, interstitial micelles composed of the minority A(2) endblock are observed to arrange into two-dimensional hexagonal arrays along the midplane of B-rich lamellae in compositionally symmetric (50:50 A:B) copolymers. Simulations performed here establish the coupled molecular-asymmetry and incompatibility conditions under which such micelles form, as well as the temperature dependence of their aggregation number. Beyond an optimal length of the A(2) endblock, the propensity for interstitial micelles to develop decreases, and the likelihood for colocation of both endblocks in the A(1)-rich lamellae increases. Interestingly, the strong-segregation theory of Semenov developed to explain the formation of free micelles by diblock copolymers accurately predicts the onset of interstitial micelles confined at nanoscale dimensions between parallel lamellae.
authors: Faculty of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland.
authors: Sebastian
authors: S
authors: Woloszczuk
authors: Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors: Kenneth P
authors: KP
authors: Mineart
authors: Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA and Department of Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors: Richard J
authors: RJ
authors: Spontak
authors: Faculty of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland.
authors: Michal
authors: M
authors: Banaszak