Highly Conductive Ionic-Liquid Gels Prepared with Orthogonal Double Networks of a Low-Molecular-Weight Gelator and Cross-Linked Polymer

Abstract

We prepared a heterogeneous double-network (DN) ionogel containing a lowmolecular-weight gelator network and a polymer network that can exhibit high ionic conductivity and high mechanical strength. An imidazolium-based ionic liquid was first gelated by the molecular self-assembly of a low-molecular-weight gelator (benzenetricarboxamide derivative), and methyl methacrylate was polymerized with a cross-linker to form a cross-linked poly(methyl methacrylate) (PMMA) network within the ionogel. Microscopic observation and calorimetric measurement revealed that the fibrous network of the low-molecular-weight gelator was maintained in the DN ionogel. The PMMA network strengthened the ionogel of the lowmolecular-weight gelator and allowed us to handle the ionogel using tweezers. The orthogonal DNs produced ionogels with a broad range of storage elastic moduli. DN ionogels with low PMMA concentrations exhibited high ionic conductivity that was comparable to that of a neat ionic liquid. The present study demonstrates that the ionic conductivities of the DN and singlenetwork, low-molecular-weight gelator or polymer ionogels strongly depended on their storage elastic moduli.

Palmitoylated amino acids as low-molecular-weight gelators for ionic liquids

“…retained the ionic conductivities of their respective ILs, even at gelator concentrations of 3 wt.%. These results agree well with previous reports, in which the ionic conductivities of ionogels were not affected by LMWG concentrations [17,24,30,31]. The constant conductivity may have resulted from the vacant space between nanofibers, in which ions could move as freely in the gel state as in the liquid state [17,24,30,31].…”

“…Ionogels consist of an IL immobilized in a polymer matrix, and gelation to form ionogels is an effective strategy in immobilizing ILs. Ionogels have been synthesized using organic polymer-based gelation [13][14][15][16][17], inorganic polymer-based gelation [18][19][20] and low-molecular-weight gelators (LMWGs) or supramolecular gelators [21][22][23][24][25][26][27][28][29][30][31].…”

Preparation of High‐Performance Ionogels with Excellent Transparency, Good Mechanical Strength, and High Conductivity

“…Comparing with the recently reported ILs‐based heterogeneous double networks that are generated either by using ILs as the continuous phase in uncharged cross‐linked polymer networks or copolymerizing IL monomers with uncharged monomers, our designed ionogels in the present work exhibit several advantages: i) the one‐component double network, i.e., PAMPS‐based double network, endows the ionogel with excellent optical transparency, higher than 95%, which cannot be achieved by previous heterogeneous double networks; and ii) the mechanical strength and conductivity of our ionogel is better than previous IL‐based double networks. For example, the compressive strength of our ionogel (7.7 MPa at 92% strain) is superior to that by molecular self‐assembly of a low‐molecular‐weight gelator in an imidazolium‐based IL, and subsequent introduction of cross‐linked poly(methyl methacrylate) (0.95 MPa at 55% strain) . Moreover, conductivity of our ionogel (1.9 S m −1 ) is 2.4 times higher than that in ref.…”

“…As shown in Figure c, the compressive strength of the designed double‐network ionogel reaches 7.7 MPa at 92% strain, which is significantly enhanced comparing with single‐network ionogel. This value is also much higher than mechanical strength of ionogel prepared by using self‐initiated UV polymerization (1.7 MPa at 95% strain), and orthogonal double‐network ionogel, comprising a low‐molecular‐weight gelator network and a cross‐linked poly(methyl methacrylate) network (0.95 MPa at 58% strain) . Also, our ionogel is much more ductile than ionogel with tetra‐poly(ethylene glycol) (PEG) network, which is about 80% strain under 7.5 MPa pressure.…”

Zwitterionic Copolymer‐Supported Ionogel Electrolytes: Impacts of Varying the Zwitterionic Group and Ionic Liquid Identities

“…Polymer-supported, liquid-rich electrolyte composites (i. e. gel electrolytes) represent a broad class of solid, non-flowing electrolyte materials that can offer high ionic conductivities using a diverse array of liquid electrolyte and polymer scaffold components. Polymer-supported hydrogels containing mobile ions, [14,15] ionic liquid-based gels (ionogels), [16][17][18][19][20][21][22][23][24][25] and deep eutectic solvent (DES) gels [26][27][28][29] are examples of widely-investigated gel electrolytes; key advantages of the latter two categories are their nonvolatility and a typically larger electrochemical stability window. [30,31] The ionic conductivity of a gel electrolyte is determined both by the concentration of mobile ions and the individual ion mobilities.…”