Phase Behavior of Polystyrene-block-poly(2-vinylpyridine) Copolymers in a Selective Ionic Liquid Solvent

Abstract

The phase behavior of poly(styrene-block-2-vinylpyridine) copolymer solutions in an imidazolium bis(trifluoromethane)sulfonamide ([Im][TFSI]) ionic liquid has been studied using small-angle X-ray scattering (SAXS) and optical transmission characterization. Through scaling analysis of SAXS data, we demonstrate that the [Im][TFSI] ionic liquid behaves as a selective solvent toward one of the blocks. We observe lyotropic and thermotropic phase transitions that correspond qualitatively to the phase behavior observed in block copolymer melts and block copolymer solutions in molecular solvents. In addition, we have studied the thermal properties of block copolymer solutions in the ionic liquid using differential scanning calorimetry and wide-angle X-ray scattering. We observe distinct composition regimes corresponding to the change in the block copolymer's glass transition temperature, Tg, with respect to the concentration of polymer in ionic liquid. At high block copolymer concentrations, a "salt-like" regime corresponding to an increase in the block copolymer Tg is observed, while at intermediate block copolymer concentrations, a "solvent-like" regime corresponding to a decrease in the block copolymer T, is observed. An unusual thermal transition consisting of crystallization and subsequent melting of the ionic liquid is observed at the lowest block copolymer concentration characterized.

Polyurethanes Containing an Imidazolium Diol‐Based Ionic‐Liquid Chain Extender for Incorporation of Ionic‐Liquid Electrolytes

“…Figure 9b plots inter‐domain d spacings (Table S2, Supporting Information) as a function of IL content (wt%), which shows that d spacing between polyurethane hard domains linearly increased with IL content. Previous studies have showed that the preferential incorporation of IL into block copolymers leads to increased d spacing due to the conformational change of polymer chains in the presence of IL 32. Segalman and co‐workers32 studied a polystyrene‐ block ‐poly(2‐vinylpyridine) block copolymer incorporated with EMIm TFSI IL, which displayed systematic increase in d spacing with IL content.…”

Poly(vinylidene fluoride) nanofibrous mats with covalently attached SiO2 nanoparticles as an ionic liquid host: enhanced ion transport for electrochromic devices and lithium-ion batteries

“…8 Meanwhile, ILs are frequently doped with lithium salts to compensate for their large ion size to further improve the device performance. [10][11][12][13] Among many IL-based polymer electrolytes, IL-loaded electrospun mats have garnered increasing interest because in the mats there are interconnected pores between the randomly laid bers, which facilitate electrolyte uptake and transport of ions. Thus, IL-based gel polymer electrolytes (GPEs), which consist of IL immobilized in a polymer matrix, are an attractive alternative to the IL-based liquid electrolytes.…”

Can ionic liquid additives be used to extend the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly?

“…[43][44][45] More recently, there have been reports on more concentrated systems where it has been demonstrated that blending ILs with BCPs such as PS-b-poly(2-vinyl pyridine), [46][47][48] PS-b-poly (ethylene oxide) 49 [PEO], and PEO-b-poly(propylene oxide)-b-PEO 50 can lead to changes in morphology and d-spacing of the phase-separated domains. In this study, we blend 1-ethyl-3-methylimidazolium …”