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Redox‐Switchable Supramolecular Graft Polymer Formation via Ferrocene–Cyclodextrin Assembly
Author(s) -
Szillat Florian,
Schmidt Bernhard V. K. J.,
Hubert Artur,
BarnerKowollik Christopher,
Ritter Helmut
Publication year - 2014
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201400122
Subject(s) - polymer chemistry , polymerization , chain transfer , copolymer , comonomer , reversible addition−fragmentation chain transfer polymerization , supramolecular chemistry , raft , polymer , cyclodextrin , chemistry , ferrocene , aqueous solution , materials science , radical polymerization , organic chemistry , molecule , electrode , electrochemistry
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 ‐dimethylacrylamide (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 (M ¯ n= 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).