The Influence of Monomer Structure on the Properties of Ionogels Obtained by Thiol–Ene Photopolymerization

Abstract

The influence of ene and thiol monomer structure on the mechanical and electrochemical properties of thiol–ene polymeric ionogels were investigated. Ionogels were obtained in situ by thiol–ene photopolymerization of 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATT), 2,4,6-triallyloxy-1,3,5-triazine (TAT), diallyl phthalate (DAP), and glyoxal bis(diallyl acetal) (GBDA) used as enes and trimethylolpropane tris(3-mercaptopropionate) (TMPTP), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), and pentaerythritol tetrakis(3-mercaptobutyrate) (PETMB) used as thiols in 70 wt.% of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImNTf2). The mechanical strength of ionogels was studied by puncture resistance and ionic conductivity by electrochemical impedance spectroscopy. The course of photopolymerization by photo-DSC method (differential scanning calorimetry) as well as characterization of compositions and its components (by IR and UV spectroscopy-Kamlet–Taft parameters) were also studied. The resulting ionogels were opaque, with phase separation, which resulted from the dispersion mechanism of polymerization. The mechanical and conductive properties of the obtained materials were found to be largely dependent on the monomer structure. Ionogels based on triazine monomers TAT and TATT were characterized by higher mechanical strength, while those based on aliphatic GBDA had the highest conductivity. These parameters are strongly related to the structure of the polymer matrix, which is in the form of connected spheres. The conductivity of ionogels was high, in the range of 3.5–5.1 mS∙cm−1.

Gel Polymer Electrolytes with Mixture of Triazolium Ionic Liquids and Propylene Carbonate

“…As can be seen, after removing the solvent from the ionogel’s structure, the opacity of the samples decreases, which indicates phase separation of the components of the prepared ionogels. Our previous research confirms that the photopolymerization reaction between thiol and ene in an ionic liquid occurs as dispersion polymerization [ 22 , 26 ]. This kind of reaction starts with a homogeneous solution of the monomer in an appropriate solvent.…”

“…Using appropriate reagents, i.e., 4-nitroaniline, ( , >99%), N , N -diethyl-4-nitroaniline ( , 98%), and Reichardt’s dye ( , 90%), all delivered by Sigma-Aldrich the empirical Kamlet–Taft polarity parameters (hydrogen bond donating ability— α ; hydrogen bond accepting ability— β ; dipolarity/polarizability— π *), as well as Reichardt’s empirical polarity parameters ( (30) and normalized were determined. Solvatochromic parameters were estimated according to the method described previously [ 26 ] using spectrophotometer Jasco UV-530 (Tokyo, Japan) and calculated according to Equations (1)–(5) and methods presented in the references [ 27 , 28 , 29 , 30 ]: in which and are nitroaniline reagents N , N -diethyl-4-nitroaniline and 4-nitroaniline, respectively, and is Reichardt’s dye.…”

“…Puncture resistance tests on the CT3 texture analyzer (Ametek Brookfield, Middleboro, MA, USA) were selected for studies of the mechanical properties of prepared ionogels. These studies were carried out according to the methodology described in the previous work [ 26 ]. Briefly, a sample (16 mm) was mounted in a holder (hole 10 mm) and tested for puncture resistance with the probe (cylindrical, Ø 5 mm, displacement rate 0.3 mm·s −1 ).…”

Optimization of Ionogel Polymer Electrolytes Composition for Their Best Performance in Electric Double Layer Capacitor

“…Our previous works devoted to the synthesis of ionogels by thiol-ene photopolymerization [18,22] allowed obtaining materials with a good ionic conductivity and flexibility but with a quite low mechanical strength. This can be associated with flexible thioether linkages which are formed during the reaction, long cross-linking sites, as well as a homogenous polymer network.…”

“…Additionally, the composition was modified with aliphatic urethane diacrylate (AUDA) in order to improve the mechanical properties. Based on the preliminary studies, [22] lower and upper limits were introduced in the mixture composition. In the case of PETMP, the maximum content of this monomer was 50 wt.…”