Tuning Arm Architecture Leads to Unusual Phase Behaviors in a (BAB)5 Star Copolymer Melt

• DOI: 10.1021/acs.macromol.8b01484
• Publication Date: 2018-11-29T16:09:11Z
• Authors: Lei Chen; Yicheng Qiang; Weihua Li
• Keywords: Star (game theory); Volume fraction; Reentrancy

The self-assembly behavior of (B1AB2)5 star copolymers, composed five asymmetric BAB-triblock arms joined at the end B2-blocks, has been investigated using self-consistent field theory. special architecture enables a few different sophisticated mechanisms such as conformational asymmetry from topology, effect combinatorial entropy multiple that enhances formation bridging configurations for core local segregation between two B-blocks, and solubilization short B2-block in majority A-domain, each which individually demonstrated to play an important role impacting block copolymers before. As result, combination these leads many unusual phase behaviors with tunable τ = fB1/(fB1 + fB2) where fB1 fB2 are volume fractions B1- respectively. For example, reentrant transitions BCC FCC spherical phases observed minority A-domains, whereas width overall region opposite side diagram exhibits maxima increases. expansion first maximum is induced by reduced effective fraction due thus solely occupied phase. While second originates enlarged "core–shell" domains segregation, leading complex Frank–Kasper phases. In addition, no stable gyroid A-network 4/5, while expanded significantly. absence very rare phenomenon here may result combined mechanisms.