Anionic Polymerization of <i>para</i>-(1-Ethoxy ethoxy)styrene: Rapid Access to Poly(<i>p</i>‑hydroxystyrene) Copolymer Architectures

Living anionic polymerization of <i>para</i>-(1-ethoxy ethoxy)­styrene (<i>p</i>EES) resulting in molecular weights between 2700 and 69 000 g mol^–1 and polydispersity indices ≤1.09 is introduced. P<i>p</i>EES can be used as a precursor for the synthesis of well-defined poly­(<i>p</i>-hydroxystyrene) (PHS) architectures, enabling facile and rapid acidic deprotection at room temperature within a few minutes. In addition, a series of block copolymers containing <i>p</i>EES and 2-vinylpyridine (2VP) have been synthesized by anionic block copolymerization, with varied block ratios (<i>X</i>_2VP) between 0.13 and 0.83. Characterization by ¹H NMR spectroscopy, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) was carried out, and all polymers have been deprotected, leading to the respective PHS-<i>b</i>-P2VP block copolymers. Furthermore, PHS-<i>b</i>-P2VP has been used as a macroinitiator for the anionic ring-opening polymerization of ethylene oxide (EO) to generate ((PHS-<i>g</i>-PEO₅₁)₁₃-<i>b</i>-P2VP₄₀) graft-block copolymers

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 (<i>M</i>_w/<i>M</i>_n < 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 <i>in situ</i> 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 homopolymers of fcGE was studied by cyclic voltammetry (CV). In order to demonstrate possible postmodification reactions, the random copolymers were modified with <i>N</i>-acetyl-l-cysteine methyl ester via a thiol–ene addition. All polymers have furthermore been characterized by ¹H NMR spectroscopy, DOSY ¹H NMR spectroscopy, size exclusion chromatography (SEC), and MALDI-ToF mass spectrometry

Functional Group Distribution and Gradient Structure Resulting from the Living Anionic Copolymerization of Styrene and <i>para</i>-But-3-enyl Styrene

The functional group distribution along the polymer backbone resulting from the living anionic copolymerization of styrene (S) and <i>para</i>-but-3-enyl styrene (<i>p</i>BuS) was investigated in cyclohexane at room temperature. A variety of copolymers with different comonomer contents <i>x</i>(S) = 0–0.84 have been synthesized with molecular weight dispersities <i>M</i>_w/<i>M</i>_n ≤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 monomer concentration of each monomer in stock throughout the reaction. Consequently, monomer incorporation and thus the probability of incorporation can be determined at any time of the copolymerization, and a precise determination of the functional group density along the polymer chain is possible. To demonstrate accessibility of the olefin side chains of the copolymer for transformations, quantitative thiol–ene addition of a cysteine derivative has been studied

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(ferrocenyldimethylsilane-<i>b</i>-ethylene oxide) block copolymers with a low polydispersity index. All polymers have been characterized by ¹H NMR spectroscopy, DOSY ¹H NMR spectroscopy, size exclusion chromatography (SEC), and MALDI-ToF mass spectrometry. In addition, for the characterization of the morphology of the PFDMS-<i>b</i>-PEO block copolymers transmission electron microscopy (TEM) was performed in methanol, confirming the formation of cylindrical micelles with an organometallic core and polyether corona

Redox-Responsive Block Copolymers: Poly(vinylferrocene)‑<i>b</i>‑poly(lactide) Diblock and Miktoarm Star Polymers and Their Behavior in Solution

The synthesis of diblock and miktoarm star polymers containing poly­(vinylferrocene) (PVFc) and poly­(l-lactide) (PLA) blocks is introduced. End functionalization of PVFc was carried out via end capping of living carbanionic PVFc chains with benzyl glycidyl ether (BGE). By hydrogenolysis of the benzyl protecting group a dihydroxyl end-functionalized PVFc was obtained. Both monohydroxyl- and dihydroxyl-functionalized PVFcs have been utilized as macroinitiators for the subsequent polymerization of l-lactide via catalytic ring-opening polymerization. A series of block copolymers and AB₂ miktoarm star polymers was synthesized with varied PLA chain lengths. All polymers were characterized in detail, using ¹H NMR spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF). The molecular weight of the block copolymers and AB₂ miktoarm star polymers are in the range of 8000–15000, containing a PVFc block of weight 7800. In addition, the self-assembly behavior of the polymers in dichloromethane (CH₂Cl₂) was investigated by using dynamic light scattering (DLS) and transmission electron microscopy (TEM). In a selective solvent for PLA the block copolymers and miktoarm star polymers formed vesicle-like structures with different diameters

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 mixing device leading to a turbulent mixing patternhas been achieved. Both setups allow living anionic polymerization in polar solvents at room temperature with full monomer conversion within seconds and yield polymers with narrowly distributed molecular weights. A maximum <i>M</i>_n of approximately 149,000 g mol^–1 (PS-9, PDI = 1.04) for PS and 96,000 g mol^–1 for P2VP (P2VP-15, PDI = 1.05) was obtained. Clearly, the turbulent four-way jet mixing device led to lower polydispersity than the laminar mixing device. All polymers were characterized by ¹H NMR spectroscopy and size exclusion chromatography (SEC)