0000000000000315
AUTHOR
Arda Alkan
Water-soluble and redox-responsive hyperbranched polyether copolymers based on ferrocenyl glycidyl ether
Water-soluble copolymers of ferrocenyl glycidyl ether (fcGE) and glycidol were prepared via anionic ring-opening multibranching polymerization (ROMBP). The resulting hyperbranched materials with molecular weights (Mn) of 3500 to 12 300 g mol−1 and relatively narrow molecular weight distributions (Mw/Mn = 1.40–1.69) exhibit both temperature- as well as redox-responsive behavior, which was studied via turbidity measurements. The cloud point temperatures (Tc) were adjusted between 45 and 60 °C through variation of the fcGE comonomer content. Additionally, these Tcs can be increased by the addition of an oxidizing agent. The extent of oxidation of the materials was quantified by Mosbauer spectr…
Ferrocenyl Glycidyl Ether: A Versatile Ferrocene Monomer for Copolymerization with Ethylene Oxide to Water-Soluble, Thermoresponsive Copolymers
The first ferrocene-containing epoxide monomer, ferrocenyl glycidyl ether (fcGE), is introduced. The monomer has been copolymerized with ethylene oxide (EO). This leads to electroactive, water-soluble, and thermoresponsive poly(ethylene glycol) (PEG) derived copolyethers. Anionic homo- and copolymerization of fcGE with EO was possible. Molecular weights could be varied from 2000 to 10 000 g mol–1, resulting in polymers with narrow molecular weight distribution (Mw/Mn = 1.07–1.20). The ferrocene (fc) content was varied from 3 to 30 mol %, obtaining water-soluble materials up to 10 mol % incorporation of the apolar ferrocenyl comonomer. Despite the steric bulk of fcGE, random copolymers were …
Functional Group Distribution and Gradient Structure Resulting from the Living Anionic Copolymerization of Styrene and para-But-3-enyl Styrene
The functional group distribution along the polymer backbone resulting from the living anionic copolymerization of styrene (S) and para-but-3-enyl styrene (pBuS) was investigated in cyclohexane at room temperature. A variety of copolymers with different comonomer contents x(S) = 0–0.84 have been synthesized with molecular weight dispersities Mw/Mn ≤1.12. All polymers have been characterized in detail by 1H NMR spectroscopy, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC). A detailed understanding of the monomer sequence distribution during the copolymerization was achieved by real-time 1H NMR spectroscopy. This technique permits us to determine the changing …
Enlarging the Toolbox: Epoxide Termination of Polyferrocenylsilane (PFS) as a Key Step for the Synthesis of Amphiphilic PFS-Polyether Block Copolymers.
Epoxide termination and functionalization of living poly(ferrocenyldimethylsilane) (PFDMS) is introduced by precapping the living PFDMS with a 4/2 molar mixture of 1,1-diphenylethylene and 1,1-dimethylsilacyclobutane acting as a “carbanion pump” system. Subsequent addition of allyl glycidyl ether (AGE) leads to quantitatively functionalized PFDMS–AGE polymers with molecular weights between 1500 and 15 400 g mol–1 and polydispersity indices ≤1.10, carrying one hydroxyl group and an additional allylic double bond. PFDMS–AGE was then applied as a macroinitiator for the living anionic ring-opening polymerization of ethylene oxide (EO) to generate amphiphilic and water-soluble poly(ferrocenyldim…
Vinyl ferrocenyl glycidyl ether: an unprotected orthogonal ferrocene monomer for anionic and radical polymerization
The first orthogonal ferrocene monomer, vinyl ferrocenyl glycidyl ether (VfcGE), for both anionic and radical polymerization – without the need of a protection group – is presented. Anionic ring-opening copolymerization of VfcGE and ethylene oxide (EO) generates stimuli-responsive, multifunctional poly[(vinyl ferrocenyl glycidyl ether)-co-(ethylene oxide)] (P[VfcGE-co-EO]) copolymers (molecular weights of ca. 7500 g mol−1 and low molecular weight dispersities (Đ ≤ 1.14)). The amount of the equimolar ferrocenyl and vinyl groups are controlled by the comonomer ratio up to 15.4 mol% VfcGE. The pendant vinyl groups of P[VfcGE-co-EO] were post-modified with 3-mercaptopropionic acid via thiol–ene…
Living Anionic Polymerization in Continuous Flow: Facilitated Synthesis of High-Molecular Weight Poly(2-vinylpyridine) and Polystyrene
We describe the living anionic polymerization of 2-vinylpyridine (2VP) and styrene (S) in continuous flow, comparing two micromixing devices with different mixing principles. The use of a continuous flow setup reduces the experimental effort for living anionic polymerizations significantly, compared to a conventional batch system. By adjusting the ratio of the flow rates of the monomer and initiator solutions a variety of different molecular weights can be rapidly synthesized within several minutes, using one setup. Additionally, a comparison of the influence of the two different mixing devices—an interdigital micromixer (SIMM-V2) leading to laminar mixing and a tangential four-way jet mixi…
Ferrocene-Containing Multifunctional Polyethers: Monomer Sequence Monitoring via Quantitative 13C NMR Spectroscopy in Bulk
Ferrocenyl glycidyl ether (fcGE) and allyl glycidyl ether (AGE) are copolymerized via living anionic ring-opening polymerization to generate polyfunctional copolymers with molecular weights up to 40 300 g/mol and low molecular weight dispersities (Mw/Mn < 1.18). Copolymerizations were carried out in bulk at 100 °C and unexpectedly found to proceed without any isomerization of the allyl double bonds. The copolymerization behavior of fcGE and AGE was monitored by in situ quantitative 13C NMR kinetic measurements in bulk, evidencing the formation of random copolymers under these conditions, showing no gradient of comonomer incorporation. The redox-active behavior of the copolymers and homopoly…
Monomer Sequence Distribution Monitoring in Living Carbanionic Copolymerization by Real-Time 1H NMR Spectroscopy
Detailed understanding of the monomer sequence distribution in carbanionic copolymerization was achieved by direct online monitoring of copolymerizations in an NMR tube. Obtaining detailed knowledge of the changing monomer concentration in stock during the reaction, this technique permits to determine the incorporation probability for each monomer at every position of the polymer chain. An in situ kinetic study of two different carbanionic copolymerizations has been carried out. On the one hand, the copolymerization of the structurally similar, protected hydroxystyrene derivatives, p-(1-ethoxy ethoxy)styrene (pEES) and 4-tert-butoxystyrene (tBuOS), and on the other hand the copolymerization…