title: Redox-switchable supramolecular graft polymer formation via ferrocene-cyclodextrin assembly.
abstract: The redox switchable formation of very well-defined supramolecular graft polymers in aqueous solution driven by host-guest interactions between ferrocene (Fc) and cyclodextrin (CD) is presented. The Fc-containing acrylic backbone copolymer (PDMA-stat-Fc) is prepared via reversible addition-fragmentation chain transfer (RAFT) copolymerization of N,N-dimethyl-acrylamide (DMA) and the novel monomer N-(ferrocenoylmethyl)acrylamide (NFMA). Via the RAFT process, copolymers containing variable Fc ratios (5-10 mol%) are prepared, affording polymers of molecular masses of close to 11,000 g mol(-1) and molar mass dispersities (Đ) of 1.2. The β-cyclodextrin (β-CD) containing building block is synthesized via RAFT-polymerization, too, in order to afford a polymer with well-defined molecular mass and low dispersity (Mn = 10 300 g mol(-1) , Đ = 1.1), employing a propargyl-functionalized chain transfer agent for the polymerization of N,N-diethylacrylamide (DEA). The polymerization product is subsequently terminated with β-CD via the regiospecific copper (I)-catalyzed 1,3-cycloaddition (PDEA-βCD). Host-guest interactions between Fc and CD lead to the formation of supramolecular graft-polymers, verified via nuclear Overhauser enhancement spectroscopy (NOESY). Importantly, their redox-responsive character is clearly confirmed via cyclic voltammetry (CV). The self-assembly of the statistical Fc-containing lateral polymer chain in aqueous solution leads to mono- and multi-core micelle-aggregates evidenced via TEM. Only diffused cloud-like, non-spherical nanostructures are observed after addition of PDEA-βCD (TEM).
authors.affiliation: Lehrstuhl für Präparative Polymerchemie, Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine Universität, Universitätsstraße 1, Geb. 26.33.00, 40225, Düsseldorf, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Szillat
authors.forename: Bernhard V K J
authors.initials: BV
authors.lastname: Schmidt
authors.forename: Artur
authors.initials: A
authors.lastname: Hubert
authors.forename: Christopher
authors.initials: C
authors.lastname: Barner-Kowollik
authors.forename: Helmut
authors.initials: H
authors.lastname: Ritter
mesh_terms: D020106:Acrylamide / Q000737:chemistry; D003505:Cyclodextrins / Q000737:chemistry*; D055664:Electrochemical Techniques; D005296:Ferrous Compounds / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D000075163:Metallocenes; D049329:Nanostructures / Q000737:chemistry; D010084:Oxidation-Reduction; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D003505:Cyclodextrins; D005296:Ferrous Compounds; D005609:Free Radicals; D000075163:Metallocenes; D011108:Polymers; D020106:Acrylamide; C004998:ferrocene
keywords: RAFT polymerization; cyclodextrin; ferrocene; redox polymers; supramolecular structures