Curable Ionic Liquid Prepolymer-Based Ion Gel Coating System for Toxic Industrial Chemical Hazard Mitigation on Porous Substrates

A peelable gel coating based on a curable ammonium-alcohol ionic liquid (IL) prepolymer has been developed for the decontamination of toxic industrial chemicals (TICs) from porous substrates. The physical properties of these coatings can be tuned by controlling the prepolymer molecular weight (prepared by RAFT polymerization) and by altering the formulation of the initial coating mixture. The initially applied (uncured) solutions can be applied onto porous wood and ceramic substrates with minimal soak-in, and these films cure quickly in situ under ambient conditions. These coatings were tested in a series of assays meant to demonstrate their effectiveness as TIC vapor barriers and materials that absorb liquid TICs from the aforementioned substrates. The coatings were found to suppress ∼80% of the vapor released by a TIC simulant (<i>o</i>-dichlorobenzene) from these substrates and to extract up to 85% of the mass of the originally applied simulant that soaked into these substrates

Ionic Liquid Gel-Based Containment and Decontamination Coating for Blister Agent-Contacted Substrates

Current methods to contain and decontaminate materials contacted by toxic chemical warfare agents (CWAs) have disadvantages with respect to ease of delivery, portability, and effectiveness on porous substrates. A portable, easy-to-use, spreadable coating that immediately acts as a barrier to contain CWA vapors on contacted substrates and also decontaminates soaked-in CWAs is highly desired. A new type of decontaminating barrier coating for sulfur mustard (i.e., blister agent) CWAs has been developed that is made of (1) a spreadable nonvolatile, fluid matrix based on a room-temperature ionic liquid (RTIL), (2) an organic gelator that acts as a solidifying agent to help the applied coating adhere to and prevent runoff from angled or vertical surfaces, and (3) a polyamine that acts as a reagent to chemically degrade and help draw out adsorbed blister agent. When applied to porous and nonporous substrates contacted with 2-chloroethyl ethyl sulfide (CEES, a mustard agent simulant), this spreadable, soft solid coating was found to act as an effective barrier, blocking 70–90% of the CEES vapor from entering the overhead space compared to uncoated samples. Furthermore, this reactive gel RTIL coating was able to remove (i.e., draw out and degrade) 70–95% of the liquid CEES soaked into porous substrates after 24 h at ambient temperature when applied as a static, single-application coating. Preliminary studies with added dyes and indicators to this coating system have shown that the decontamination process may be followed visually via color changes

Curable Imidazolium Poly(ionic liquid)/Ionic Liquid Coating for Containment and Decontamination of Toxic Industrial Chemical-Contacted Substrates

A curable, imidazolium-based room-temperature ionic liquid (RTIL) coating system has been developed for the containment and decontamination of toxic industrial chemical-contacted surfaces. The curing times and mechanical properties of this poly­(RTIL)/RTIL platform, which is based on alcohol–isocyanate step-growth polymerization chemistry, can be tuned by modifying the structures of the step-growth monomers, the stoichiometric ratio of linear (diol, <b>A</b>_<b>2</b>) to cross-linking (triol, <b>A</b>_<b>3</b>) RTIL monomers used, and the amount of free RTIL in the formulation. When applied to painted steel and rubber test substrates contacted with <i>o</i>-dichlorobenzene (<i>o</i>-DCB) (a polychlorinated biphenyl simulant), a 50:50 (<b>A</b>_<b>2</b>:<b>A</b>_<b>3</b>) step-growth alcohol-RTIL monomer mixture cross-linked with a stoichiometric amount of a commercial di-isocyanate monomer (<b>B</b>_<b>2</b>) and containing 43 wt % free RTIL in the coating, reduced the <i>o</i>-DCB vapor amount by 96–99% compared to the uncoated, <i>o</i>-DCB-contacted control samples. This peelable, flexible, solid coating also removed by sorption up to >99% of the <i>o</i>-DCB liquid applied to the substrates after 24 h of contact

Effect of Monomer Structure on Curing Behavior, CO₂ Solubility, and Gas Permeability of Ionic Liquid-Based Epoxy–Amine Resins and Ion-Gels

New imidazolium- and pyrrolidinium-based bis­(epoxide)-functionalized ionic liquid (IL) monomers were synthesized and reacted with multifunctional amine monomers to produce cross-linked, epoxy–amine poly­(ionic liquid) (PIL) resins and PIL/IL ion-gel membranes. The length and chemical nature (i.e., alkyl versus ether) between the imidazolium group and epoxide groups were studied to determine their effects on CO₂ affinity. The CO₂ uptake (millimoles per gram) of the epoxy–amine resins (between 0.1 and 1 mmol/g) was found to depend predominately on the epoxide-to-amine ratio and the bis­(epoxide) IL molecular weight. The effect of using a primary versus a secondary amine-containing multifunctional monomer was also assessed for the resin synthesis. Secondary amines can increase CO₂ permeability but also increase the time required for bis­(epoxide) conversion. When either the epoxide or amine monomer structure is changed, the CO₂ solubility and permeability of the resulting PIL resins and ion-gel membranes can be tuned

Vinyl-Functionalized Poly(imidazolium)s: A Curable Polymer Platform for Cross-Linked Ionic Liquid Gel Synthesis

Vinyl-Functionalized Poly(imidazolium)s: A Curable Polymer Platform for Cross-Linked Ionic Liquid Gel Synthesi

Ideal CO₂/Light Gas Separation Performance of Poly(vinylimidazolium) Membranes and Poly(vinylimidazolium)-Ionic Liquid Composite Films

Six vinyl-based, imidazolium room-temperature ionic liquid (RTIL) monomers were synthesized and photopolymerized to form dense poly­(RTIL) membranes. The effect of polymer backbone (i.e., poly­(ethylene), poly­(styrene), and poly­(acrylate)) and functional cationic substituent (e.g., alkyl, fluoroalkyl, oligo­(ethylene glycol), and disiloxane) on ideal CO₂/N₂ and CO₂/CH₄ membrane separation performance was investigated. The vinyl-based poly­(RTIL)­s were found to be generally less CO₂-selective compared to analogous styrene- and acrylate-based poly­(RTIL)­s. The CO₂ permeability of <i>n</i>-hexyl- (69 barrers) and disiloxane- (130 barrers) substituted vinyl-based poly­(RTIL)­s were found to be exceptionally larger than that of previously studied styrene and acrylate poly­(RTIL)­s. The CO₂ selectivity of oligo­(ethylene glycol)-functionalized vinyl poly­(RTIL)­s was enhanced, and the CO₂ permeability was reduced when compared to the <i>n</i>-hexyl-substituted vinyl-based poly­(RTIL). Nominal improvement in CO₂/CH₄ selectivity was observed upon fluorination of the <i>n</i>-hexyl vinyl-based poly­(RTIL), with no observed change in CO₂ permeability. However, rather dramatic improvements in both CO₂ permeability <i>and</i> selectivity were observed upon blending 20 mol % RTIL (emim Tf₂N) into the <i>n</i>-hexyl- and disiloxane-functionalized vinyl poly­(RTIL)­s to form solid–liquid composite films

A Highly Breathable Organic/Inorganic Barrier Material that Blocks the Passage of Mustard Agent Simulants

Garment materials that provide protection against exposure to toxic chemical warfare agents (CWAs) not only require the ability to block the passage of these toxic compounds in vapor form but also the ability to transport water vapor to allow cooling for the wearer. Only a very limited number of examples of such “breathable” CWA barrier materials are known. A new type of reactive organic/inorganic composite film material is presented that has a very high water vapor transport rate (>1800 g m^–2 day^–1 for a 220-μm-thick film) and the ability to completely block penetration of the mustard agent simulant, 2-chloroethyl ethyl sulfide (CEES), after 22 h of continuous exposure. This new composite material is based on two components: (1) a cross-linked, diol-functionalized room-temperature ionic liquid polymer that serves as a dense, flexible hydrophilic matrix, and (2) a basic zeolite (sodium zeolite-Y (NaY)) that serves as an inexpensive, nucleophilic additive that chemically degrades the CEES as it enters the film. Preliminary FT-IR studies on this new reactive barrier material suggest that the OH groups on the ionic polymer not only facilitates water vapor transport but may also help activate mustard-type vapors for reaction with the imbedded NaY

Effect of counter-ion on the thermotropic liquid crystal behaviour of bis(alkyl)-tris(imidazolium salt) compounds

<div><p>Recently, new thermotropic ionic liquid crystals (LCs) with a hexyl-linked tris(imidazolium bromide) core and two terminal alkyl chains were synthesised and characterised. To explore the effect of different counter-ions on the LC behaviour of this system, derivatives with BF₄⁻ and Tf₂N⁻ counter-ions were prepared and analysed. Five of the BF₄⁻ derivatives were found to exhibit thermotropic LC behaviour. The 12-, 14- and 16-carbon tail BF₄⁻ compounds form SmA phases. The 18- and 20-carbon tail homologues form what appears to be a smectic phase but are weakly mesogenic and harder to characterise. Only two of the Tf₂N⁻ derivatives exhibited mesogenic behaviour. The 18-carbon tail Tf₂N⁻ compound forms an as-yet unidentified, highly periodic smectic phase with positional order while the 20-carbon tail homologue forms a periodic SmA phase. The Tf₂N⁻ mesogens have much lower clearing points even though their LC phases have more order than the Br⁻ and BF₄⁻ mesogens. X-ray diffraction showed that these mesogens have different amounts of tail interdigitation between the smectic layers depending on the counter-ion present. Atomistic molecular dynamics simulations indicated that counter-ion size plays an important role in defining the density of the ionic region, which in turn affects the amount of interdigitation in the smectic phases.</p></div

Glycerol-Based Bicontinuous Cubic Lyotropic Liquid Crystal Monomer System for the Fabrication of Thin-Film Membranes with Uniform Nanopores

Glycerol-Based Bicontinuous Cubic Lyotropic Liquid Crystal Monomer System for the Fabrication of Thin-Film Membranes with Uniform Nanopore

Morphological Phase Behavior of Poly(RTIL)-Containing Diblock Copolymer Melts

The development of nanostructured polymeric systems containing directionally continuous poly­(ionic liquid) (poly­(IL)) domains has considerable implications toward a range of transport-dependent, energy-based technology applications. The controlled, synthetic integration of poly­(IL)­s into block copolymer (BCP) architectures provides a promising means to this end, based on their inherent ability to self-assemble into a range of defined, periodic morphologies. In this work, we report the melt-state phase behavior of an imidazolium-containing alkyl–ionic BCP system, derived from the sequential ring-opening metathesis polymerization (ROMP) of imidazolium- and alkyl-substituted norbornene monomer derivatives. A series of 16 BCP samples were synthesized, varying both the relative volume fraction of the poly­(norbornene dodecyl ester) block (<i>f</i>_DOD = 0.42–0.96) and the overall molecular weights of the block copolymers (<i>M</i>_n values from 5000–20 100 g mol^–1). Through a combination of small-angle X-ray scattering (SAXS) and dynamic rheology, we were able to delineate clear compositional phase boundaries for each of the classic BCP phases, including lamellae (Lam), hexagonally packed cylinders (Hex), and spheres on a body-centered-cubic lattice (S_BCC). Additionally, a liquid-like packing (LLP) of spheres was found for samples located in the extreme asymmetric region of the phase diagram, and a persistent coexistence of Lam and Hex domains was found in lieu of the bicontinuous cubic gyroid phase for samples located at the intersection of Hex and Lam regions. Thermal disordering was opposed even in very low molecular weight samples, detected only when the composition was highly asymmetric (<i>f</i>_DOD = 0.96). Annealing experiments on samples exhibiting Lam and Hex coexistence revealed the presence of extremely slow transition kinetics, ultimately selective for one or the other but not the more complex gyroid phase. In fact, no evidence of the bicontinuous network was detected over a 2 month annealing period. The ramifications of these results for transport-dependent applications targeting the use of highly segregated poly­(IL)-containing BCP systems are carefully considered