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

Abstract

A curable, imidazolium-based room-temperature ionic liquid (RTIL) coating system has been developed for the containment and decontamination of toxic industrial chemicalcontacted 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, A 2 ) to cross-linking (triol, A 3 ) RTIL monomers used, and the amount of free RTIL in the formulation. When applied to painted steel and rubber test substrates contacted with o-dichlorobenzene (o-DCB) (a polychlorinated biphenyl simulant), a 50:50 (A 2 :A 3 ) step-growth alcohol-RTIL monomer mixture cross-linked with a stoichiometric amount of a commercial di-isocyanate monomer (B 2 ) and containing 43 wt % free RTIL in the coating, reduced the o-DCB vapor amount by 96−99% compared to the uncoated, o-DCB-contacted control samples. This peelable, flexible, solid coating also removed by sorption up to >99% of the o-DCB liquid applied to the substrates after 24 h of contact.

Cross-linked, polyurethane-based, ammonium poly(ionic liquid)/ionic liquid composite films for organic vapor suppression and ion conduction

“…GC-MS measurements were performed using a Thermo-Finnigan PolarisQ Ion Trap GC-MS system with a column containing a stationary phase of 5% phenyl and 95% methyl polysiloxane. GC-MS analyses were performed over a temperature range of 100 °C to 300 °C [30]. Ionic conductivity was determined by potentiostatic electrical impedance tests using a Gamry Instruments Reference 600 Potentiostat/Galvanostat/ZRA.…”

“…Polyurethane S-G chemistry (i.e., the reaction of multifunctional alcohol monomers with multifunctional isocyanate monomers) was selected due to its rapid reaction speed, control over linear polymer molecular weight and degree of cross-linking in network formation, and lack of volatile byproducts produced during reaction [49] (which is an important consideration in organic vapor containment applications [29,30]). In addition, it was important that the chemical structures of the IL monomers and the composition of the S-G polymerization mixtures (including the amount of linear vs. cross-linking monomers and the amount of free IL incorporated) be easily varied, in order to tune certain physical properties (i.e., flexibility, curing time) of the resulting cross-linked PIL/IL materials.…”

“…The multifunctional isocyanate monomer, TDI (Scheme 1) was selected due to its prevalence in industrial polyurethane resin production, its low cost, and its commercial availability. Additionally, recent work by Martin et al showed that TDI is fairly soluble in ILs (for IL-based polymerizations) and that it was the fastest curing di-isocyanate monomer for use with imidazolium-alcohol IL-based polyurethane reactions compared to other commercially available di-isocyanates [30]. Although TDI itself is not an ILbased monomer, its ability to be dissolved in ILs affords sufficiently low vapor release in IL-solventbased polymerizations for applications requiring low vapor release, such as organic vapor containment [13].…”

“…FT-IR spectroscopy was used to monitor the kinetics of the curing reaction of the individual ammonium-diol and -triol IL monomers with TDI with added free IL under the conditions described in Table 1, using protocols based on a prior paper for monitoring imidazolium-alcohol IL monomers reacting with TDI [30]. These curing tests were selected in order to simulate conditions in which the curable PIL/IL coating would be applied.…”

“…We characterized the gel curing times of the ammonium IL diol and triol monomers as a function of their structure, and the thermal and mechanical properties of free-standing cross-linked PIL/IL films as a function of their composition. We also evaluated the resulting cross-linked PIL/IL films for their thermal stability under air and inert atmosphere, their ability to act as sorptive barrier coatings for volatile toxic organic liquids [29,30], and their variable-temperature ion conductivity behavior. In general, we found that these new ammonium step-growth PIL/IL composites have better thermal stability than previously reported ammonium-based PILs and PIL/IL blends [15,17,25,28,[31][32][33][34][35][36][37].…”