title: pH-regulated selectivity in supramolecular polymerizations: switching between Co- and homopolymers.
abstract: A strategy is presented to regulate the selectivity in aqueous supramolecular polymerizations by changes in pH. In neutral buffered conditions, oppositely charged phenylalanine-based dendritic peptide amphiphiles self-assemble into (A-B)n alternating copolymers of low polydispersity when mixed in a 1:1 comonomer feed ratio. Via pH switch of the glutamic acid and lysine side chains, attractive Coulomb interactions in the coassembled materials are screened and selective polymerization occurs to form (A)n homopolymers of the acidic comonomer at low pH and (B)n homopolymers of the basic comonomer at high pH, while the complementary comonomer is released during the transition. Reversible switching is demonstrated between these three different polymeric states, which were characterized by CD and fluorescence spectroscopy, using a peptide based minimalistic fluorophore/quencher pair, and transmission electron microscopy.
authors.affiliation: Organic Chemistry Institute and CeNTech, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany).
authors.forename: Hendrik
authors.initials: H
authors.lastname: Frisch
authors.forename: Yan
authors.initials: Y
authors.lastname: Nie
authors.forename: Stefan
authors.initials: S
authors.lastname: Raunser
authors.forename: Pol
authors.initials: P
authors.lastname: Besenius
keywords: controlled polymerization; pH regulation; polymers; self-assembly; supramolecular chemistry