Aggregation behavior of cyclic rod-coil diblock copolymers in selective solvents

Abstract

The aggregation behavior of cyclic rod-coil (RC) diblock copolymers in dilute solutions is investigated through dissipative particle dynamics simulation. By varying the rod length and coil length, cyclic RC copolymers in selective solvents exhibit various morphologies, including spherical micelle, vesicle, bilayer disc, and ribbon bundle structure. Compared with the equivalent linear RC copolymer, only spherical micelle and barrel bundle phase are observed. Rod length is the major factor that controls the liquid-crystalline behavior of RC copolymer systems, while the coil length has a secondary effect on the aggregate morphology. The size of rod bundle varies with the coil length, especially for the end-toend ribbon bundle and side-by-side barrel bundle, which are assembled by cyclic and linear RC copolymer solutions. This finding indicates that the ribbon bundle or nanofiber-like structure in cyclic RC copolymers can be obtained by controlling the rod length and coil length, and thus the optical and electrical properties of RC copolymer would be further controlled and optimized. Results illustrate that cyclization of a linear RC copolymer induces remarkable differences in the rod arrangement and aggregation behavior, thereby indicating the competition between interfacial energy, rod orientational entropy, coil stretching entropy, and packing constraints.

Topology-Directed Coassembly of Linear and Cyclic Amphiphilic Diblock Copolymers: A Monte Carlo Study

“…The physicochemical property differences between cyclic and linear BCP systems may result in differences in their self-assembly behaviors. Many experimental, − theoretical, and simulation − studies have been carried out to reveal the influence of the topological effect on the self-assembly behavior of BCPs in solution by comparing the micellization behaviors of amphiphilic cyclic and linear BCPs. Yu et al − have prepared a series of BCPs with equal chain length but different chain architectures, including cyclic diblock copolymers of ethylene oxide (E) and 1,2-butylene oxide (B) (C-EB) as well as linear diblock (L-EB) and triblock (L-EBE) copolymers.…”