Polymerization Of Vinyl Ether Research Articles

Influence of Pendant Fluoroalkyl Segments on Properties of Fluoroethylene and Vinyl Ether Polymers and Their Hydrophobic Coatings

Influence of Pendant Fluoroalkyl Segments on Properties of Fluoroethylene and Vinyl Ether Polymers and Their Hydrophobic Coatings

Light-Controlled Cationic RAFT Polymerization of Vinyl Ethers Using N-Arylacridinium Photocatalysts

Light-Controlled Cationic RAFT Polymerization of Vinyl Ethers Using <i>N</i>-Arylacridinium Photocatalysts

Recent Developments on Cationic Polymerization of Vinyl Ethers.

In recent times, the evolution of cationic polymerization has taken a multidirectional approach, with the development of cationic reversible addition-fragmentation chain transfer (RAFT) polymerization. In contrast to the conventional cationic polymerization methods, which were typically carried out under inert atmospheres and low temperatures, various novel polymerization techniques have been developed where the reactions are carried out in open air, operate at room temperature, are cost-effective, and are environmentally friendly. Besides, several external stimuli, such as heat, light, chemicals, electrical potential, etc. have been employed to activate and control the polymerization process. It also enables the combination of cationic polymerization with other polymerization methods in a single reaction vessel, eliminating the necessity for isolation and purification during intermediate steps. In addition, significant advancements have been made through various modifications in catalyst systems, resulting in polymers with an exceptionally high level of stereoregularity. This review article comprehensively analyses the recent developments in cationic polymerization, encompassing their applications and offering insights into future perspectives.

Asymmetric Ion-Pairing Photoredox Catalysis for Stereoselective Cationic Polymerization under Light Control.

By virtue of noninvasive regulations by light, photocontrolled polymerizations have attracted considerable attention for the precision synthesis of macromolecules. However, a cationic polymerization with simultaneous photocontrol and tacticity-regulation remains elusive so far. Herein, we introduce an asymmetric ion-pairing photoredox catalysis strategy that allows for the development of a stereoselective cationic polymerization with concurrent light regulation for the first time. By employing an ion pair catalyst (PC+/*A-) consisting of a photoredox active cation (PC+) and a sterically confined chiral anion (*A-) to deliver the stereochemical control, the cationic polymerization of vinyl ethers can be achieved with photocontrol and high isotactic selectivity (up to 91% m) at a remarkable low catalyst loading (50 ppm).

Synthesis of degradable polymers via 1,5-shift radical isomerization polymerization of vinyl ether derivatives with a cleavable bond

AbstractWe report a novel method for synthesizing degradable polymers based on 1,5-shift radical isomerization polymerizations of vinyl ethers with transferable atoms or groups and in-between acid-cleavable ether linkages in the side chains. In particular, vinyl ethers with side chains composed of thiocyano and p-methoxybenzyl ether groups underwent radical isomerization polymerizations via 1,5-shifts, in which a vinyl ether radical abstracted the cyano group intramolecularly to generate a thiyl radical and result in a polymer with a p-methoxybenzyl ether linkage in the main chain. The obtained polymer was easily degraded into low molecular-weight products with HCl solution. Furthermore, the copolymerization with vinyl acetate proceeded via 1,5-shift isomerization to introduce cleavable linkages in the main chains of the copolymers, which were similarly degraded.

Dual control of stereoregularity and molecular weight in cationic polymerization of vinyl ether by tunable TADDOLs/TiCl4 initiating systems

The stereoregularity and molecular weight of poly(isobutyl vinyl ether) was simultaneously controlled by TADDOL/TiCl4 initiating systems with various aryl substituents on TADDOL.

Solving fundamental concepts in supramolecular science with functionality-tolerant living polymerizations of self-assembling monomers and dendronized monomers

The evolution and development of several examples of functionality-tolerant living polymerizations to the level of perfection that they could be employed to solve fundamental concepts in supramolecular science by living polymerization of self-assembling monomers and self-organizable dendronized monomers is briefly reviewed. The review focuses on the development of the living polymerization methodology with brief examples on how they impacted the field of self-assembly and self-organization. The first polymerization reaction discussed is the stereoselective polymerization of phenylacetylene and of other arylacetylenes to generate helical poly(arylacetylene) stereoisomers. The transition from functionality non-tolerant to functionality-tolerant stereoselective polymerizations and the evolution to functionality-tolerant living stereoselective polymerization of phenylacetylene is used as the main example of this brief review. This living polymerization methodology is followed by living polymerization of vinyl ethers, oxazolines, of group transfer polymerization, of cationic ring-opening polymerization of cyclic siloxanes combined with hydrosilylation, of ROMP of cylooxanorbornene. This brief review is concluded by a brief discussion of the capabilities of the above-mentioned living methodologies with living radical polymerizations. The numerous applications in the field of supramolecular science of these living methodologies are not reviewed. However, the reader is directed to numerous comprehensive review articles discussing these applications. The challenges that remain to be solved in all these functionality-tolerant living polymerizations are presented.

Rapid, visible light‐controlled cationic polymerization of vinyl ethers for 3D printing of chemically reprocessable networks under ambient conditions

AbstractLight‐mediated 3D printing techniques have gained significant interest due to the inherent advantages of light as external stimuli, including spatiotemporal control and easy access. As 3D printing processes require rapid polymerization, free radical or cationic polymerization methods are used. However, these polymerization reactions are limited to the production of materials with properties that cannot be chemically altered post‐printing. In this work, a rapid, open‐to‐air photo‐controlled cationic reversible addition‐fragmentation chain‐transfer polymerization of vinyl ethers is demonstrated in the presence of a three‐component photoinitiating system comprising a photosensitizer, electron donor, and acceptor as co‐initiators under the irradiation with blue light. The polymerization mechanism shows rapid kinetics and controlled, living polymerization characteristics. Trithiocarbonate chain ends of poly(isobutyl vinyl ethers) are reactivated to produce block copolymers with cyclohexyl vinyl ethers. The rapid kinetics and water tolerance of the reported system enable the 3D printing of polymeric solids under ambient (e.g., room temperature and open to air) conditions, followed by the effective reactivation of trithiocarbonate chain ends to post‐synthetically modify the object with an acrylate‐based fluorescent monomer via a controlled radical polymerization strategy.

Ortho-Alkoxy-benzamide Directed Formation of a Single Crystalline Hydrogen-bonded Crosslinked Organic Framework and Its Boron Trifluoride Uptake and Catalysis.

Boron trifluoride (BF3 ) is a highly corrosive gas widely used in industry. Confining BF3 in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF3 corrosion. Herein, we designed and synthesized a Lewis basic single-crystalline hydrogen-bond crosslinked organic framework (HC OF-50) for BF3 storage and its application in catalysis. Specifically, we introduced self-complementary ortho-alkoxy-benzamide hydrogen-bonding moieties to direct the formation of highly organized hydrogen-bonded networks, which were subsequently photo-crosslinked to generate HC OFs. The HC OF-50 features Lewis basic thioether linkages and electron-rich pore surfaces for BF3 uptake. As a result, HC OF-50 shows a record-high 14.2 mmol/g BF3 uptake capacity. The BF3 uptake in HC OF-50 is reversible, leading to the slow release of BF3 . We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF3 ⋅ Et2 O. The elucidation of the structure-property relationship, as provided by the single-crystal X-ray structures, combined with the high BF3 uptake capacity and controlled sorption, highlights the molecular understanding of framework-guest interactions in addressing contemporary challenges.

Ortho‐Alkoxy‐benzamide Directed Formation of a Single Crystalline Hydrogen‐bonded Crosslinked Organic Framework and Its Boron Trifluoride Uptake and Catalysis

AbstractBoron trifluoride (BF3) is a highly corrosive gas widely used in industry. Confining BF3 in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF3 corrosion. Herein, we designed and synthesized a Lewis basic single‐crystalline hydrogen‐bond crosslinked organic framework (HCOF‐50) for BF3 storage and its application in catalysis. Specifically, we introduced self‐complementary ortho‐alkoxy‐benzamide hydrogen‐bonding moieties to direct the formation of highly organized hydrogen‐bonded networks, which were subsequently photo‐crosslinked to generate HCOFs. The HCOF‐50 features Lewis basic thioether linkages and electron‐rich pore surfaces for BF3 uptake. As a result, HCOF‐50 shows a record‐high 14.2 mmol/g BF3 uptake capacity. The BF3 uptake in HCOF‐50 is reversible, leading to the slow release of BF3. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF3 ⋅ Et2O. The elucidation of the structure–property relationship, as provided by the single‐crystal X‐ray structures, combined with the high BF3 uptake capacity and controlled sorption, highlights the molecular understanding of framework‐guest interactions in addressing contemporary challenges.

Thermally initiated cationic frontal polymerization of epoxies and vinyl ethers through a lone onium salt

AbstractFrontal polymerization (FP) of epoxy monomers is typically achieved with a radical‐induced cationic frontal polymerization (RICFP) process that combines a thermal radical initiator with an onium salt superacid generator. In this paper, we show that both thermal and UV‐initiated cationic frontal polymerizations are possible for common epoxy and vinyl ether monomers with only an iodonium superacid generator in the absence of a standalone thermal radical initiator. Increasing superacid generator concentration resulted in an increase in front velocity, as did the addition of vinyl ether to epoxies. The front velocity is reduced by the addition of 4‐methoxyphenol (MeHQ), indicating free‐radicals play a significant role.

Mechanistic Insight into Anion‐Binding Catalytic Living Cationic Polymerization

AbstractExploiting non‐covalent interactions to catalyze challenging ionic polymerizations is an ambitious goal but is in its infancy. We recently demonstrated non‐covalent anion‐binding catalysis as an effective methodology to enable living cationic polymerization (LCP) of vinyl ethers in an environmentally benign manner. Here, we further elucidate the structure‐reactivity relationships of the elaborately designed seleno‐cyclodiphosph(V)azanes catalysts and the roles of anion‐binding interactions by a combined theoretical DFT study and experimental study. The investigation suggests that the distinct cis‐cyclodiphosph(V)azane framework combined with “selenium effect” and electron‐withdrawing 3,5‐(CF3)2‐Phenyl substitution pattern in catalyst enables a critical contribution to accessing excellent stability, anion affinity and solubility under polymerization conditions. Thus, the catalyst could leverage anion‐binding interactions to precisely control reversible and transient dormant‐active species equilibrium, allowing it to dynamically bind, recognize and pre‐organize propagating ionic species and monomer, thereby facilitating efficient chain propagation and minimizing irreversible chain transfer events under mild conditions. The more in‐depth understanding of the mechanism for anion‐binding catalytic LCP reported herein should help to guide future catalyst design and to extend this concept to broader polymerization systems where ionic species serve as crucial intermediates.

Mechanistic Insight into Anion-Binding Catalytic Living Cationic Polymerization.

Exploiting non-covalent interactions to catalyze challenging ionic polymerizations is an ambitious goal but is in its infancy. We recently demonstrated non-covalent anion-binding catalysis as an effective methodology to enable living cationic polymerization (LCP) of vinyl ethers in an environmentally benign manner. Here, we further elucidate the structure-reactivity relationships of the elaborately designed seleno-cyclodiphosph(V)azanes catalysts and the roles of anion-binding interactions by a combined theoretical DFT study and experimental study. The investigation suggests that the distinct cis-cyclodiphosph(V)azane framework combined with "selenium effect" and electron-withdrawing 3,5-(CF3 )2 -Phenyl substitution pattern in catalyst enables a critical contribution to accessing excellent stability, anion affinity and solubility under polymerization conditions. Thus, the catalyst could leverage anion-binding interactions to precisely control reversible and transient dormant-active species equilibrium, allowing it to dynamically bind, recognize and pre-organize propagating ionic species and monomer, thereby facilitating efficient chain propagation and minimizing irreversible chain transfer events under mild conditions. The more in-depth understanding of the mechanism for anion-binding catalytic LCP reported herein should help to guide future catalyst design and to extend this concept to broader polymerization systems where ionic species serve as crucial intermediates.

Tetrapodal ZnO nanomaterial synthesis for antibacterial fluoroethylene vinyl ether polymer coating

Antibacterial coatings can be nanofabricated to provide antimicrobial persistence, nanostructural tailoring, and superhydrophobicity. This study presents a method for preparing an effective antibacterial coating by introducing tetrapodal ZnO (T-ZnO) nanomaterials on a fluoroethylene vinyl ether polymer (FEVE). T-ZnO nanomaterials were as-synthesized by flame transport synthesis and characterized. The T-ZnO exhibited a tetrapodal micro- and nanostructure with four legs of ∼43 μm diameter, comprising 86.67 and 12.90 wt% of Zn and O, respectively. High-resolution images of a single leg with sharp whiskers exhibited well-developed crystallinity. The antibacterial capabilities of T-ZnO functional coatings were determined using a reaction solution consisting of FEVE directly soaked in various wt% of T-ZnO with ethyl acetate. The 10 wt% T-ZnO nanocomplex coating exhibited the best surface hydrophobicity, with a water contact angle of 155°. The proposed T-ZnO on a fluoroethylene polymer-based coating exhibited higher antibacterial efficacy toward Gram-positive S. Aureus and -negative E. Coli compared with a standard polymer-based coating. In examining cellular toxicity, no harm was found to NIH/3T3 cells using the CCK-8 assay. Hence, this study provides a simple method for preparing safe and effective antibacterial coatings for practical applications.

Organocatalytic stereoselective cationic polymerization of alkenyl vinyl ethers and post-functionalization via click chemistry

Vinyl polymer tacticity is critical for regulating the thermal and physical properties of materials. Stereoselective cationic polymerization of vinyl ethers has gained significant progress in recent years, while monomer scope beyond simple alkyl vinyl ethers to access functionalized isotactic polymer materials remains to be explored but highly desirable. Herein, we report the successful development of a stereoselective cationic polymerization of alkenyl vinyl ethers by employing confined Brønsted acid organocatalysis. This organocatalytic system shows high efficiency and stereoselectivity in the polymerization of several alkenyl vinyl ethers, as well as good compatibility to the diolefinic monomers without touching the C=C bonds in the alkenyl part during the cationic polymerization, thus allowing for further modification on these C-C double bonds after polymerization to construct functionalized, isotactic polymer materials. Further, a series of thermoplastic copolymers with tunable properties and variable and predictable contents of side-chain C=C bonds can be synthesized through the corresponding stereoselective copolymerization. Sequential post-polymerization modification of both isotactic homopolymers and copolymers by combining thiol-ene and sulfur(VI) fluoride exchange (SuFEx) click reactions is also demonstrated.

Study on the cationic polymerization of isobutyl vinyl ether initiated by dual active species based on [Ph3C][B(C6F5)4] and its mechanism

AbstractThe cationic polymerization of isobutene vinyl ether(IBVE) contains waters system was achieved by using triphenylmethylium tetrakis‐(pentafluorophenyl)borate [Ph3C][B(C6F5)4], which overcame the harsh experimental requirements of traditional cationic polymerization. The influences of water content, solvent polarity, and reaction temperature on polymerization were studied. The end structure of the polymer was analyzed by 1H‐NMR. Combined with the effect of the proton trapping agent and triethylamine salt which can trap [H+], it was found that there was a reversible equilibrium between [Ph3C+] and [H+] active species during the polymerization process. The cationic polymerizations of isobutyl vinyl ether were initiated by these two active species simultaneously. The controllable cationic polymerization of isobutyl vinyl ether was achieved by the addition of ethyl methyl carbonate and ethyl benzoate. Gaussian 09 W simulation confirms the polymerization mechanism.

Visible light‐catalyzed living cationic homopolymerization and copolymerization of isobutyl vinyl ether: Characteristics and mechanism

AbstractOn the basis of synthesizing a highly efficient chain‐transfer agent ethyl (1‐isobutoxyethyl) carbonotrithioate(CTA), living cationic polymerization of isobutyl vinyl ether (IBVE) was successfully initiated by visible light catalysis. The random copolymerization of isobutyl vinyl ether and propyl vinyl ether (PVE), cyclohexyl vinyl ether (CyVE), and 2‐chloroethyl vinyl ether (CEVE) was achieved on the basis of investigating the reactivity ratios of vinyl ether monomers. The influence of photocatalyst (PC) concentration and wavelength on the copolymerizations was investigated. It was found that high PC concentration results in a fast polymerization rate. The wavelength of the blue LED was most suitable for this reaction system. This photocatalytic reaction provides a new way for molecular design of cationic polymerization.

Fast Living 3D Printing via Free Radical Promoted Cationic RAFT Polymerization.

The application of reversible deactivation radical polymerization techniques in 3D printing is emerging as a powerful method to build "living" polymer networks, which can be easily postmodified with various functionalities. However, the building speed of these systems is still limited compared to commercial systems. Herein, a digital light processing (DLP)-based 3D printing system via photoinduced free radical-promoted cationic reversible addition-fragmentation chain transfer polymerization of vinyl ethers, which can build "living" objects by a commercial DLP 3D printer at a relatively fast building speed (12.99cm h-1 ), is reported. The polymerization behavior and printing conditions are studied in detail. The livingness of the printed objects is demonstrated by spatially controlled postmodification with a fluorescent monomer.

Facile hydrophobic modification of hydrophilic membranes by fluoropolymer coating for direct contact membrane distillation

Membrane distillation (MD) is a promising desalination technology as it is less sensitive to feed's salinity and can handle high-salinity water. However, the industrial application of MD is restricted by the limited availability of cost-effective hydrophobic membranes. This study developed a simple method to fabricate hydrophobic MD membranes through the coating of a fluoroethylene vinyl ether polymer called LUMIFLON™ LF-200. The fluoropolymer was effectively coated on porous nitrocellulose (NC) and nylon membrane through dip-coating followed by a thermal crosslinking. The coating layer was thin and uniform, covering the surface of the whole membrane matrix, while the high porosity and the microstructure of the membranes were still mostly preserved. After modification, the originally hydrophilic NC and nylon membranes were transformed into hydrophobic, with water contact angles of ∼130°. The 12LF-NC membrane showed a high flux of 10.1 kg m−2 h−1 with salt rejection >99.99% over 120 h in the direct contact MD fed with 10 wt% NaCl solution, which outperformed the commercial PVDF membrane. This coating method has the potential to modify various substrates to produce MD membranes with good performance, which broadens the availability of appropriate membranes for MD application.

The development of highly efficient monophosphonium photocatalysts for the visible light-regulated metal-free cationic polymerization of vinyl ethers

Monophosphonium salts designed via P+-doping of benzo-anthracene have been identified as a new and highly efficient class of tunable photocatalysts for the visible light-regulated cationic RAFT polymerization of vinyl ethers.