Order-to-Disorder Transitions in Lamellar Melt Self-Assembled Core-Shell Bottlebrush Polymers

Michael G Karavolias; Jack B Elder; Emily M Ness; Mahesh K Mahanthappa

doi:10.1021/acsmacrolett.9b00782

Order-to-Disorder Transitions in Lamellar Melt Self-Assembled Core-Shell Bottlebrush Polymers

ACS Macro Lett. 2019 Dec 17;8(12):1617-1622. doi: 10.1021/acsmacrolett.9b00782. Epub 2019 Nov 25.

Authors

Michael G Karavolias¹, Jack B Elder², Emily M Ness³, Mahesh K Mahanthappa^{1

2}

Affiliations

¹ Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
² Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
³ Department of Chemistry, Pacific Lutheran University, Rieke Science Center, 12180 Park Avenue S, Tacoma, Washington 98447, United States.

PMID: 35619390
DOI: 10.1021/acsmacrolett.9b00782

Abstract

We report the synthesis and melt self-assembly behaviors of densely grafted, core-shell bottlebrush (csBB) polymers derived from covalently linking narrow dispersity, symmetric composition ABA-type triblock polymers through their chain midpoints. Derived from sequential ring-opening polymerizations of ε-decalactone and rac-lactide initiated from 5-norbornene-2-exo,3-exo-dimethanol, poly(lactide-block-ε-decalactone-block-lactide) macromonomers (M_n = 9.2-17.8 kg/mol; Đ = 1.19-1.25) were enchained by living ring-opening metathesis polymerization (ROMP) into csBBs with backbone degrees of polymerization N_bb = 8-43. Temperature-dependent small-angle X-ray scattering (SAXS) studies indicate that the critical triblock arm degree of polymerization (N_arm) required for melt segregation decreases with increasing N_bb, leading to reductions in the accessible ordered lamellar microdomain (d) spacings. We derive a phenomenological relationship between the critical triblock arm segregation strength at the order-disorder transition (χN_arm)_ODT and N_bb to enable the future design of microphase separated core-shell bottlebrushes, which self-assemble at sub-10 nm length scales for nanolithography and nanotemplating applications.