Extreme Deflection of Phase Boundaries and Chain Bridging in A(BA')_n Miktoarm Star Polymers

Journal Article · 07 January 2020 · Macromolecules

DOI: https://doi.org/10.1021/acs.macromol.9b02254 · OSTI ID:1594760

Lequieu, Joshua  ^[1]; Koeper, Trenton ^[2]; Delaney, Kris T.  ^[2]; Fredrickson, Glenn H.  ^[2]

---

1. Univ. of California, Santa Barbara, CA (United States); University of California -- Santa Barbara
2. Univ. of California, Santa Barbara, CA (United States)

In this study, we use self-consistent field theory to demonstrate that the A(BA')_n miktoarm architecture can strongly deflect order–order phase boundaries to large volume fractions fA. The A(BA')n architecture achieves this strong deflection by combining the effects of miktoarm frustration and block bidispersity and is shown to stabilize discrete spheres and cylinders of the A block up to values of $$f_A$$ = 0.58 and $$f_A$$ = 0.78, respectively. Next, we analyze the prevalence of chain bridging $$ν_B$$ in both neat miktoarm melts and in homopolymer blends that form the fluctuation-stabilized “bricks and mortar” phase. These calculations demonstrate that high $$ν_B$$ and $$f_A$$ can both be simultaneously achieved with highly asymmetric miktoarm stars, a property especially useful for the design of tough thermoplastic elastomers. Lastly, we show that these miktoarms exhibit large windows of phase space where the σ and A15 Frank–Kasper phases are stable.

• Research Organization: Univ. of California, Santa Barbara, CA (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: SC0019001
• OSTI ID: 1594760
• Journal Information: Macromolecules, Journal Name: Macromolecules Journal Issue: 2 Vol. 53; ISSN 0024-9297
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English