ABSTRACT
Ionic liquids (ILs) are molten salts that are entirely composed of ions and have melting temperatures below 100 °C. When immobilized in polymeric matrices by sol-gel or chemical polymerization, they generate gels known as ion gels, ionogels, ionic gels, and so on, which may be used for a variety of electrochemical applications. One of the most significant research domains for IL-based gels is the energy industry, notably for energy storage and conversion devices, due to rising demand for clean, sustainable, and greener energy. Due to characteristics such as nonvolatility, high thermal stability, and strong ionic conductivity, IL-based gels appear to meet the stringent demands/criteria of these diverse application domains. This article focuses on the synthesis pathways of IL-based gel polymer electrolytes/organic gel electrolytes and their applications in batteries (Li-ion and beyond), fuel cells, and supercapacitors. Furthermore, the limitations and future possibilities of IL-based gels in the aforementioned application domains are discussed to support the speedy evolution of these materials in the appropriate applicable sectors.
ABSTRACT
In this work, we report the synthesis of ion-conductive gels, or ionic gels, via thiol-ene click reactions. The novel gel systems consist of the multifunctional thiol monomers tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), pentaerythritol tetrakis(3-mercaptopropionate) (PEMP), and dipentaerythritol hexakis(3-mercaptopionate) (DPMP) as joint molecules and bifunctional allyl ionic liquid (IL) as a crosslinker. The thiol-ene reaction was carried out in lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) in a propylene carbonate (PC) (1 M) solvent system via a photopolymerization process. The chemical structure and mechanical, thermal, and conductive properties of the gels were investigated using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), compression tests, and impedance spectroscopy, respectively. The mechanical and conductive properties of the ionic gels were found to be largely dependent on the monomer content and functionalities of the joint molecules. TGA revealed good thermal stability of the gels up to 100 °C. An ionic conductivity of 4.89 mS cm-1 was realized at room temperature (298 K) for low-functional thiol monomers, and a further increase in ionic conductivity was observed with an increase in Li+ ion content and temperature.
ABSTRACT
3D food printing sectors require comprehensive knowledge on viscoelastic and mechanical properties of diverse food materials in order to effectively utilize them in rapid and customized 3D production for supply and manufacturing chains. In this work, we present mechanical and rheological properties of Agar and Konjac based edible gels at different Agar and Konjac weight ratio and discuss their 3D printing performance. Gel samples with higher Konjac content positively contributed to the viscoelastic properties of the gel samples which in return has been found viable for extrusion-based 3D printing. By choosing appropriate printing parameters, different shapes are printed to demonstrate printing resolution. We expect, this study will add potential scope for evaluating and optimizing soft-gel materials for 3D food printing sector.
ABSTRACT
In this work, we present the structural analysis of 3D/4D printable N,N-dimethylacrylamide (DMAAm)-co-stearyl acrylate (SA) and/or lauryl acrylate (LA)-based shape memory gels (SMGs). We characterized these gels by scanning microscopic light scattering technique (SMILS) where a time- and space-averaged correlation function is obtained to overcome the inhomogeneous media. Thus, the characteristic size of the gel internal network (mesh size, ξ) and crosslinking densities are estimated from the Einstein-Stokes formula. The rheological study of the SMGs revealed information about their mechanical strength and transition temperature. From the experimental storage modulus measured by rheological study, crosslinking density and mesh size of the network were also calculated. Both the techniques suggest that SMG with high crystalline content of SA monomer in the gel network contain smaller mesh size (1.13 nm for SMILS and 9.5 nm for rheology study) and high crosslinking density. The comparative study between the light scattering technique and rheological analysis through the quantitative analysis of crosslinking densities will be important to understand the structural properties of the SMGs.
ABSTRACT
Porous polymers have been synthesized by Michael addition reactions of multi-functional acrylate and diamine or dithiol compounds. Aza-Michael addition reaction of multi-functional acrylate, trimethylolpropane propoxylate triacrylate (TPT) and hexamethylene diamine (HDA) in dimethyl sulfoxide (DMSO) successfully yielded the porous polymer. The porous structure was characterized by connected globules or co-continuous structure, and could be controlled by the reaction conditions. Mechanical properties of the porous polymers were investigated by compression test. The porous polymers with co-continuous structure showed higher Young's modulus than those with connected globules. The porous polymer absorbed some organic solvents, especially CHCl3. The porous polymer as prepared in DMSO state showed coloring induced by Christiansen filter effect depending on the reaction time and observation temperature. The thio-Michael addition reaction of TPT and 1,6-hexanedithiol (HDT) in DMSO using different base catalysts also yielded the porous polymer. The porous structure could be controlled by the catalysts amount when the reaction was initiated by a photo-base generator as the base catalyst. The present reaction systems make it possible to synthesize the porous polymers with simple process without phase separator.
ABSTRACT
Utilization of soft material like hydrogels for task-specific applications such as in soft robotics requires freedom in the manufacturing process and designability. Here, we have developed highly robust thermoresponsive poly(dimethyl acrylamide-co-stearyl acrylate and/or lauryl acrylate) (PDMAAm-co-SA and/or LA)-based shape memory gels (SMGs) using a customized optical 3D gel printer. This process enabled rapid and moldless fabrication of SMGs with a variety of shapes and sizes. By varying the compositions of the constituent monomers, a wide variety of SMGs with tunable mechanical, thermal, optical and swelling properties have been obtained. Printed SMGs with excellent fixity and recovery ratios have exhibited a wide range of values of Young's modulus (0.04-17.35 MPa) and strain (612-2363%) at room temperature when the acrylate co-monomer (SA and LA) content was varied and the value of strain has been found to be enhanced at elevated temperatures. Thermogravimetric analysis (TGA) of the SMGs shows one step peak degradation (407-417 °C) regardless of composition after an initial mass loss due to water evaporation. Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) revealed variable transition temperatures (29-49.5 °C) depending on the SA and LA content. SMGs with all of the composition ratios possess high transparency with variable swelling degrees in water and different organic solvents and exhibit refractive index values in the range of intraocular lenses, making them suitable for applications in the optical field. These unique properties of 3D printed SMGs with free formability and tunable properties are expected to generate rapid demand in a variety of sectors in biomedicine, robotics and sensing applications.