Room temperature ionic liquids (RTILs) have been a major focal point in many areas of chemistry and engineering due to their favorable properties and emerging capabilities. RTILs are popular as solvents for green chemistry due to their near-zero vapor pressure and negligible flammability. Their high ionic conductivity, stability, and selectivity for certain light gases make them attractive for energy applications such as batteries and post-combustion gas separation membranes. In circumstances where the mechanical properties of a solid polymer are more desirable, researchers have turned to polymerized ionic liquids (PILs), or polymers that incorporate a portion of the ionic liquid into each repeat unit of the polymer chain. Some PIL homopolymers, however, remain quite liquid like, a problem which can be solved by integrating the PIL into a phase separating block copolymer (BCP) architecture that takes advantage of the physical properties of two or more unique polymers. Additionally, the BCP phase separation process can produce nanostructures that can dramatically change the macroscopic properties of the material. For each new PIL BCP that is synthesized, a thorough investigation of the morphological phase separation behavior is necessary to fully understand the material to facilitate further use in application based research.

RTILs can also be incorporated into non-ionic BCPs by forming composite ion gel membranes. We utilize a sphere-forming, poly(styrene-b-ethylene oxide) diblock and triblock copolymer blend that can form a highly regular, physically crosslinked, highly elastic network capable of selectively solvating the ionic liquid and maintaining good mechanical properties even at RTIL content of over 90% by mass.¹ However, minor flaws or tears in the gel can cause catastrophic failure of the material when under mechanical stress. We aim to prevent crack and tear propagation in these ion gels by chemically modifying chain ends with the capability to preferentially break under stress and immediately catalyze the formation of new tethers between crosslinked domains to prevent propagation of tears through the material.

(1)          Wijayasekara, D. B.; Cowan, M. G.; Lewis, J. T.; Gin, D. L.; Noble, R. D.; Bailey, T. S. Elastic Free-Standing RTIL Composite Membranes for CO2/N2 Separation Based on Sphere-Forming Triblock/Diblock Copolymer Blends. J. Memb. Sci. 2016, 511, 170–179