title: Gel phase formation in dilute triblock copolyelectrolyte complexes.
abstract: Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.|Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, USA.
authors.forename: Samanvaya
authors.initials: S
authors.lastname: Srivastava
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Marat
authors.initials: M
authors.lastname: Andreev
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Adam E
authors.initials: AE
authors.lastname: Levi
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Goldfeld
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.|Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Mao
authors.affiliation: Biology &Soft Matter Division, Oak Ridge National laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: William T
authors.initials: WT
authors.lastname: Heller
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
authors.forename: Vivek M
authors.initials: VM
authors.lastname: Prabhu
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.|Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, USA.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: de Pablo
authors.affiliation: Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA.|Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, USA.
authors.forename: Matthew V
authors.initials: MV
authors.lastname: Tirrell