Atom transfer radical polymerization of ionic liquid monomer: The influence of salt/counterion on polymerization

Antibacterial Zirconia Surfaces from Organocatalyzed Atom-Transfer Radical Polymerization

Antibacterial coatings are becoming increasingly attractive for application in the field of biomaterials. In this framework, we developed polymer coating zirconia with antibacterial activity using the "grafting from" methodology. First, 1-(4-vinylbenzyl)-3-butylimidazolium chloride monomer was synthesized. Then, the surface modification of zirconia substrates was performed with this monomer via surface-initiated photo atom transfer radical polymerization for antibacterial activity. X-ray photoelectron spectroscopy, ellipsometry, static contact angle measurements, and an atomic force microscope were used to characterize the films for each step of the surface modification. The results revealed that cationic polymers could be successfully deposited on the zirconia surfaces, and the thickness of the grafted layer steadily increased with polymerization time. Finally, the antibacterial adhesion test was used to evaluate the antibacterial activity of the modified zirconia substrates, and we successfully showed the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains.

Polymerized and Colloidal Ionic Liquids─Syntheses and Applications

The breadth and importance of polymerized ionic liquids (PILs) are steadily expanding, and this review updates advances and trends in syntheses, properties, and applications over the past five to six years. We begin with an historical overview of the genesis and growth of the PIL field as a subset of materials science. The genesis of ionic liquids (ILs) over nano to meso length-scales exhibiting 0D, 1D, 2D, and 3D topologies defines colloidal ionic liquids, CILs, which compose a subclass of PILs and provide a synthetic bridge between IL monomers (ILMs) and micro to macro-scale PIL materials. The second focus of this review addresses design and syntheses of ILMs and their polymerization reactions to yield PILs and PIL-based materials. A burgeoning diversity of ILMs reflects increasing use of nonimidazolium nuclei and an expanding use of step-growth chemistries in synthesizing PIL materials. Radical chain polymerization remains a primary method of making PILs and reflects an increasing use of controlled polymerization methods. Step-growth chemistries used in creating some CILs utilize extensive cross-linking. This cross-linking is enabled by incorporating reactive functionalities in CILs and PILs, and some of these CILs and PILs may be viewed as exotic cross-linking agents. The third part of this update focuses upon some advances in key properties, including molecular weight, thermal properties, rheology, ion transport, self-healing, and stimuli-responsiveness. Glass transitions, critical solution temperatures, and liquidity are key thermal properties that tie to PIL rheology and viscoelasticity. These properties in turn modulate mechanical properties and ion transport, which are foundational in increasing applications of PILs. Cross-linking in gelation and ionogels and reversible step-growth chemistries are essential for self-healing PILs. Stimuli-responsiveness distinguishes PILs from many other classes of polymers, and it emphasizes the importance of segmentally controlling and tuning solvation in CILs and PILs. The fourth part of this review addresses development of applications, and the diverse scope of such applications supports the increasing importance of PILs in materials science. Adhesion applications are supported by ionogel properties, especially cross-linking and solvation tunable interactions with adjacent phases. Antimicrobial and antifouling applications are consequences of the cationic nature of PILs. Similarly, emulsion and dispersion applications rely on tunable solvation of functional groups and on how such groups interact with continuous phases and substrates. Catalysis is another significant application, and this is an historical tie between ILs and PILs. This component also provides a connection to diverse and porous carbon phases templated by PILs that are catalysts or serve as supports for catalysts. Devices, including sensors and actuators, also rely on solvation tuning and stimuli-responsiveness that include photo and electrochemical stimuli. We conclude our view of applications with 3D printing. The largest components of these applications are energy related and include developments for supercapacitors, batteries, fuel cells, and solar cells. We conclude with our vision of how PIL development will evolve over the next decade.

Solution and Film Self-Assembly Behavior of a Block Copolymer Composed of a Poly(ionic Liquid) and a Stimuli-Responsive Weak Polyelectrolyte

Cu(0)-mediated atom transfer radical polymerization was used to synthesize a poly(ionic liquid), poly[4-vinylbenzyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide] (PVBBImTf2N), a stimuli-responsive polyelectrolyte, poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA), and a novel block copolymer formed from these two polymers. The synthesis of the block copolymer, poly[2-(dimethylamino) ethyl methacrylate]-block-[poly(4-vinylbenzyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide] (PDMAEMA-b-PVBBImTf2N), was examined to evaluate the control of "livingness" polymerization, as indicated by molecular weight, characterizations of degree of polymerization, and 1HNMR spectroscopy. 2D DOSY NMR measurements revealed the successful formation of block copolymer and the connection between the two polymer blocks. PDMAEMA-b-PVBBImTf2N was further characterized for supramolecular interactions in both the bulk and solution states through FTIR and 1H NMR spectroscopies. While the block copolymer demonstrated similar intermolecular behavior to the PIL homopolymer in the bulk state as indicated by FTIR, hydrogen bonding and counterion interactions in solution were observed in polar organic solvent through 1H NMR measurements. The DLS characterization revealed that the PDMAEMA-b-PVBBImTf2N block copolymer forms a network-like aggregated structure due to a combination of hydrogen bonding between the PDMAEMA and PIL group and electrostatic repulsive interactions between PIL blocks. This structure was found to collapse upon the addition of KNO3 while still maintaining hydrogen bonding interactions. AFM-IR analysis demonstrated varied morphologies, with spherical PDMAEMA in PVBBImTf2N matrix morphology exhibited in the region approaching the film center. AFM-IR further revealed signals from silica nano-contaminates, which selectively interacted with the PDMAEMA spheres, demonstrating the potential for the PDMAEMA-b-PVBBImTf2N PIL block copolymer in polymer-inorganic nanoparticle composite applications.

Immobilization of molecule-based ionic liquids: a promising approach to improve elecrocatalyst performance towards the hydrogen evolution reaction

Ionic liquids (ILs) have received continuous attention owing to their unique chemical and physical properties and to their successful integration in several applications.

Highly selective adsorption of hydroquinone by hydroxyethyl cellulose functionalized with magnetic/ionic liquid

Magnetic hydroxyethyl cellulose/ionic liquid (MHEC/IL) materials were fabricated through a facile and fast process and their application as excellent adsorbents for hydroquinone was also demonstrated. The thermal stability, chemical structure and magnetic property of the MHEC/IL were characterized by the Scanning electron microscope (SEM), Transmission Electron Microscope (TEM), Fourier transform infrared spectrometer (FT-IR) and X-ray diffraction (XRD), respectively. The adsorbents were used for the removal of hydroquinone from simulated wastewater with a fast solid-liquid separation in the presence of external magnetic field. The influence of various analytical parameters on the adsorption of hydroquinone such as pH, contact time and initial ion concentration were studied in detail. The results showed that the maximum adsorption capacity was 335.68mgg^-1, observed at pH 5 and temperature 30°C. Equilibrium adsorption was achieved within 30min. The kinetic data, obtained at the optimum pH 5, could be fitted with a pseudo-second order equation. Adsorption process could be well described by Freundlich adsorption isotherms. The obtained results indicated that the impregnation of the room temperature IL significantly enhances the removal efficiency of hydroquinone. The MHEC/IL may be suitable materials in phenols pollution cleanup if they are synthesized in largescale and at low price in near future.

Synthesis of Monodisperse Silica Particles Grafted with Concentrated Ionic Liquid-Type Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization for Use as a Solid State Polymer Electrolyte

A polymerizable ionic liquid, N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEMM-TFSI), was polymerized via copper-mediated atom transfer radical polymerization (ATRP). The polymerization proceeded in a living manner producing well-defined poly(DEMM-TFSI) of target molecular weight up to about 400 K (including a polycation and an counter anion). The accurate molecular weight as determined by a GPC analysis combined with a light scattering measurement, and the molecular weight values obtained exhibited good agreement with the theoretical values calculated from the initial molar ratio of DEMM-TFSI and the monomer conversion. Surface-initiated ATRP on the surface of monodisperse silica particles (SiPs) with various diameters was successfully performed, producing SiPs grafted with well-defined poly(DEMM-TFSI) with a graft density as high as 0.15 chains/nm². Since the composite film made from the silica-particle-decorated polymer brush and ionic liquid shows a relatively high ionic conductivity, we have evaluated the relationship between the grafted brush chain length and the ionic conductivity.

Tetrakis(dialkylamino)phosphonium Polyelectrolytes Prepared by Reversible Addition-Fragmentation Chain Transfer Polymerization

A tetrakis(dialkylamino)phosphonium cation ([P(NR₂)₄]⁺) was appended to a styrenic monomer and explored in reversible addition-fragmentation chain transfer polymerization (RAFT) to conduct random copolymerizations of the cationic monomer with styrene. Well-defined polyelectrolytes with molecular weights up to ∼30 100 and dispersities between ∼1.2 and 1.4 were obtained. Up to 18.9 mol % of the ionic monomer could be incorporated into the polymer with hexafluorophosphate or bis(trifluoromethane)sulfonimide acting as the counterion during polymerization. Differential scanning calorimetry of the hexafluorophosphate polymers revealed glass transition temperatures higher than polystyrene likely due to interactions between the anion and the polymer. Thermogravimetric analysis indicated these materials have high thermal stability with decomposition temperatures approaching 400 °C.

Poly(ionic liquid)s with controlled architectures and their use in the making of ionogels with high conductivity and tunable rheological properties

We describe the preparation as well as the electrochemical and mechanical properties of a series of novel well-defined poly(ionic liquids) (PILs) featuring a finely tuned cross-linking ratio.

Thiazolium Poly(ionic liquid)s: Synthesis and Application as Binder for Lithium-Ion Batteries

We report a synthetic route to thiazolium-type poly(ionic liquid)s (PILs), which can be applied as a polymeric binder in lithium-ion batteries. The ionic liquid monomers were first synthesized by quaternization reaction of 4-methyl-5-vinyl thiazole with methyl iodide, followed by anion exchange reactions to replace iodide by fluorinated anions to access a liquid state below 100 °C. Subsequently, these monomers bearing thiazolium cations in their structure underwent radical polymerizations in bulk to produce corresponding polymers. The dependence of solution and thermal properties of such monomeric and polymeric materials on the choice of the counteranion was investigated. Finally, the thiazolium-type PIL bearing a bis(trifluoromethanesulfonyl)imide (TFSI) anion was proven to be a high performance binder for lithium-ion battery electrodes.

Preparation of an Antibacterial Poly(ionic liquid) Graft Copolymer of Hydroxyethyl Cellulose

Poly(ionic liquid)s (P(IL)s) of different degrees of polymerization (10, 50, and 100) were prepared via RAFT polymerization using an alkyne-terminated xanthate as transfer agent, with a monomer conversion of up to ∼80% and a ĐM of 1.5 for P(IL)100. Subsequently, P(IL) chains were coupled to (15)N-labeled azido-functionalized hydroxyethyl cellulose (HEC), forming graft copolymers of HEC with different chain length and graft densities, which were characterized using ((13)C and (15)N) CP-MAS NMR and FT-IR spectroscopies. The antibacterial activities of HEC-g-P(IL)s were tested against Escherichia coli and Staphylococcus aureus and were comparable to ampicillin, a well-known antibiotic, demonstrating efficient activity of the graft copolymers against bacteria. Moreover, HEC-g-P(IL)s were slightly more effective against E. coli than S. aureus. A decrease in graft density of P(IL)10 on the HEC backbone decreased the activity of the graft copolymers against both bacteria. These findings suggest that HEC-g-P(IL) could find applications as an antiseptic compound, for example, in paint formulation.

Tuning the Pore Size in Gradient Poly(ionic liquid) Membranes by Small Organic Acids

Highly charged porous polymer membranes with adjustable pore size and gradient pore structure along the membrane cross-section were prepared by ammonia-triggered electrostatic complexation between an imidazolium-based cationic poly(ionic liquid) (PIL) and multivalent benzoic acid derivatives. The PIL and the acid compound were first dissolved homogeneously in DMSO, cast into a thin film onto a glass plate, dried, and finally immersed into an aqueous ammonia solution. The diffusion of ammonia from the top to the bottom into the film neutralized the acid and introduced the gradient pore structure and in situ electrostatic cross-linking to fix the pores. The pore size and its distribution of the membranes were found controllable in terms of the multivalency of the acids, the imidazolium/carboxylate ratio, and the nature of the PIL counteranion.

Direct Route to Well-Defined Poly(ionic liquid)s by Controlled Radical Polymerization in Water

The precision synthesis of poly(ionic liquid)s (PILs) in water is achieved for the first time by the cobalt-mediated radical polymerization (CMRP) of N-vinyl-3-alkylimidazolium-type monomers following two distinct protocols. The first involves the CMRP of various 1-vinyl-3-alkylimidazolium bromides conducted in water in the presence of an alkyl-cobalt(III) complex acting as a monocomponent initiator and mediating agent. Excellent control over molar mass and dispersity is achieved at 30 °C. Polymerizations are complete in a few hours, and PIL chain-end fidelity is demonstrated up to high monomer conversions. The second route uses the commercially available bis(acetylacetonato)cobalt(II) (Co(acac)₂) in conjunction with a simple hydroperoxide initiator (tert-butyl hydroperoxide) at 30, 40, and 50 °C in water, facilitating the scaling-up of the technology. Both routes prove robust and straightforward, opening new perspectives onto the tailored synthesis of PILs under mild experimental conditions in water.