(Invited) Development of Ionic Porous Polymer for Sensing Applications

Abstract

Porous polymers with macr/micro- sized pores have potential applications in separation, batteries, fuel cells and sensors [1, 2]. Thiol-ene "click" is a widespread method for monolith preparation owing to its exceptional versatility, simplicity and facile tunability. In our previous work, we reported on the fabrication of extremely soft type thiol-ionic gels (T-IGs) incorporating ionic liquid (IL) (70–85 wt%) in the thiol–ene network of thiol-based end-crosslinker and acrylate monomers [3, 4]. The T-IGs exhibited tunable mechanical and conductive properties and conductivity as high as 5.40 mS cm−1 is attained for longer acrylate group containing gels at room temperature. In this work we developed a series of porous polymers through polymerization induced phase separation by utilizing thiol-ene reaction between multi-functional thiol monomers and diacrylate crosslinkers in ionic Liquid solvent medium. The matrix of the polymers constructed of interconnected micro-globules forming a three-dimensional network. These microporous polymers exhibited tunable mechanical prosperities and morphology. In contrary to the ionic gels, the porous structure with entrapped ILs exhibited high ionic conductivity possibly due to relatively unperturbed transport of ions within the interconnected polymer particles compared to the bulk polymeric network. Physical properties of these porous ionic polymers have been investigated to optimize suitable condition for best performance in piezoresistive sensors (enabling sensing of both pressure and strain). This work is expected to add potential functionality in the applied field of the polymer materials.References Sakakibara, K., Kagata, H., Ishizuka, N., Sato, T., Tsujii, Y. Fabrication of surface skinless membranes of epoxy resin-based mesoporous monoliths toward advanced separators for lithium ion batteries. J. Mater. Chem. A, 5, 6866–6873 (2017).Liu, Z., Ou, J., Zou, H., Click polymerization for preparation of monolithic columns for liquid chromatography. Trends Anal. Chem., 82, 89–99 (2016).Ahmed, K., Naga, N., Kawakami, M. & Furukawa, H. Development of ionic gels using thiol-based monomers in ionic liquid. 9800,980005 (2016).Ahmed K, Naga N., Kawakami M. and Furukawa H., Extremely Soft, Conductive and Transparent Ionic Gels by 3D Optical Printing, Macromol. Chem. Phys., 1800216 (2018).