(181bc) ABC Polymeric Ionic Liquid Triblock Terpolymers | AIChE

(181bc) ABC Polymeric Ionic Liquid Triblock Terpolymers

Authors 

Lathrop, P. - Presenter, Texas A&M University
Elabd, Y., Texas A&M University
Polymeric ionic liquid (PIL) block copolymers are a distinct set of block copolymers that incorporate the unique physiochemical properties of PILs (e.g., high solid-state ionic conductivity, high chemical, thermal and electrochemical stability, and widely tunable physical properties) into block copolymer architecture, which allows for self-assembly into a range of nanostructures where morphology type and domain size are tunable. Recently, PIL block copolymers have been synthesized by several research groups and have shown to possess distinct conductivity-morphology relationships that have now impacted several applications, e.g., batteries, fuel cells.1 However, almost all reports are exclusive to (AB) diblock copolymers.Although AB diblock copolymers can provide orthogonal properties of high ion conduction and high mechanical strength in a solid-state material, there are limitations to AB diblock copolymers, such as a limited set of morphologies, domain sizes, and the lack of a means to achieve a combination of more than two properties simultaneously (e.g., conductivity, strength, flexibility). Moreover, spatially connected 3D network morphologies, which often result in the highest ion conductivities, occur only over a small compositional range in AB diblock copolymers. Compared to AB diblock copolymers, multiblock polymers (e.g., ABC) produce more morphology types, more 3D network morphology types, and a broader composition range to achieve 3D network morphologies.

In this study, an ABC PIL triblock terpolymer was synthesized to explore a PIL-containing polymer with a richer compliment of properties, a wider diversity of cation/backbone chemistries, and a broader compositional range to obtain a variety of continuous 3D network morphologies. Specifically, poly(S-b-VBMPyr-TFSI-b-HMA)was synthesized viasequential reversible addition-fragmentation chain-transfer (RAFT) polymerization and subsequently quaternized, where A block = styrene (S), B block or PIL block = vinylbenzyl methylpyrrilidonium bis(trifluoromethylsulfonyl)imide(VBMPyr-TFSI), and C block = hexyl methacrylate (HMA). Reaction kinetics of this PIL ABC triblock terpolymer were investigated and these results were utilized in scaling up the polymerization reaction to > 200 g quantities with narrow polydispersities and controllable block compositions. Chemical, thermal, morphological, and ion conductive properties were characterized using 1H nuclear magnetic resonance (NMR) spectroscopy, elemental analysis (EA), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and electrical impedance spectroscopy (EIS).

  1. Meek, K. M.; Elabd, Y. A., Polymerized ionic liquid block copolymers for electrochemical energy. J Mater Chem A 2015, 3(48), 24187-24194.