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Various overoxidized poly(1H-pyrrole) (PPy), poly(N-methylpyrrole) (PMePy) or poly(3,4-ethylenedioxythiophene) (PEDOT) membranes incorporated into an acrylate-based solid polymer electrolyte matrix (SPE) were directly electrosynthesized by a two-step in situ procedure. The aim was to extend and improve fundamental properties of pure SPE materials. The polymer matrix is based on the cross-linking of glycerol propoxylate (1PO/OH) triacrylate (GPTA) with poly(ethylene glycol) diacrylate (PEGDA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a conducting salt. A self-standing and flexible polymer electrolyte film is formed during the UV-induced photopolymerization of the acrylate precursors, followed by an electrochemical polymerization of the conducting polymers to form a 3D-IPN. The electrical conductivity of the conducting polymer is destroyed by electrochemical overoxidation in order to convert the conducting polymer into an ion-exchange membrane by introduction of electron-rich groups onto polymer units. The resulting polymer films were characterized by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, differential scanning calorimetry, thermal analysis and infrared spectroscopy. The results of this study show that the combination of a polyacrylate-matrix with ion selective properties of overoxidized CPs leads to new 3D materials with higher ionic conductivity than SPEs and separator or selective ion-exchange membrane properties with good stability by facile fabrication.
The current study presents a new class of functional derivatives (1–3) consisting of a dicationic viologen (4,4’-bipyridinium unit) (V21) capped by nucleobases thymine (NB1), adenine (NB2), thymine/adenine (NB1, NB2), and ion-paired with amphiphilic anion 3,4,5-tris(dodecyloxy)benzene sulfonate (DOBS-). The target of our work focuses on the design and synthesis of molecular building blocks in which three different functionalities are combined: chromophore (V21 unit), molecular recognition (NB unit), and thermotropic liquid crystal (DOBS unit). The resulted materials exhibit liquid crystalline properties at ambient temperature with significant particularities-induced by nucleobases in the mesogen structure. Structure–properties relationship study focuses on providing knowledge about (1) how the thermotropic, redox properties, thermochromism, or ionic conductive properties are influenced by the presence of purinic or pyrimidinic nucleobases, and (2) how effective is their ability to selfassembly by hydrogen bonding in nonpolar solvents. The presence of nucleobases has been proved to have a substantial impact on electron transfer rate during the reduction of viologen moieties by intermolecular aggregation. Ionic conductivity and thermochromic properties of derivatives 1–3 were investigated and compared to a non-containing nucleobase analog methyl viologen with 3,4,5 tris(dodecyloxy)benzene sulfonate anion (MV) as reference.
A systematic study was performed to understand the effects of the devulcanizing agent dibenzamido diphenyl disulfide (DBD) on the vulcanization and devulcanization process of a sulfur-cured ethylene-propylene-diene monomer (EPDM) rubber. The influence of DBD on vulcanization was investigated by mixing DBD with virgin rubber and curative system. The devulcanization of rubber waste was achieved with varying amounts of DBD ranging from 0.4 to 13.8 wt% and temperatures from 150 to 200°C. The quality of vulcanizates and devulcanizates was evaluated by rheometer tests, temperature scanning stress relaxation measurements, and analysis of mechanical properties. During vulcanization, DBD acts as an accelerator in the presence of sulfur. When accelerators are added, the scorch time increases, and the cure rate decreases. Thus, DBD acts as a retarder. In the presence of activators, DBD leads to a significant reduction of crosslink density. This results in composites with high elongation at break and poor compression set values. The efficiency of the devulcanization of rubber waste depends strongly on DBD concentration and temperature. The monosulfidic crosslinks are cleaved by low concentrations of DBD, while polysulfidic crosslinks require higher concentrations. These results show that DBD is effective as a devulcanizing agent and degrades the network below 200°C.