2015 journal article

Dual modes of self-assembly in superstrongly segregated bicomponent triblock copolymer melts

PHYSICAL REVIEW E, 91(1).

By: S. Woloszczuk*, K. Mineart n, R. Spontak n & M. Banaszak*

co-author countries: Poland 🇵🇱 United States of America 🇺🇸
Source: Web Of Science
Added: August 6, 2018

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 ${A}_{1}B{A}_{2}$ 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.