Poly(ether–thioethers) by Thiol–Ene Click and Their Oxidized Analogues as Lithium Polymer Electrolytes

Abstract

A family of nine poly(ether−thioethers) (PETEs) were synthesized by the radical coupling of a dithiol and a divinyl ether to investigate the importance of organosulfur incorporation in solid polymer electrolytes. Two series of four polymers each were synthesized to probe both the effect of the carbon spacer length between thioether units and of the ratio of ether to thioether units. PETE samples from these two series had low T g values, ranging from −50 to −75 °C, and all but two PETEs displayed crystallinity. Molecular weights between 7 and 13 kg/mol were obtained for all polymers. Taking advantage of the sulfur-centered functional group, a single polymer, PETE-1, was selectively oxidized to the poly(ether−sulfoxide) PESO-1 and the poly(ether−sulfone) PES-1. Oxidation increased the T g of PETE-1 from −64 °C to −36 and −26 °C for PESO-1 and PES-1, respectively, while all three were amorphous. Of the nine new PETE polymers, two were amorphous and the addition of LiTFSI decreased the extent of crystallinity for the other seven PETE samples. An increase in T g was also observed for PETE-1, PESO-1, and PES-1 with the addition of salt. PETE samples with carbon spacers of two, four, and six methylene units had generally uniform ion conductivity, near 5 × 10 −5 S/cm at 80 °C, while the sample with eight methylene units had a lower conductivity that was further decreased by crystallinity at lower temperatures. Samples with varied ether and thioether ratios also had very uniform conductivities, similar in magnitude to samples with varied carbon spacers. Within the oxidized series, PETE-1 outperformed PES-1, which in turn outperformed PESO-1 in terms of ion mobility. The highest observed conductivity (10 −4 S/cm) at 80 °C was for PETE-1 with a salt loading of r = 0.05. The synthetic approach described here will enable a wealth of new polymer structures to be produced with controlled functional group placement and density providing novel materials for solid polymer electrolytes, broad functional group variation, and comprehensive structure− activity relationships.

Fatty Acid–Derived Aliphatic Long Chain Polyethers by a Combination of Catalytic Ester Reduction and ADMET or Thiol‐Ene Polymerization

“…M n seems to increase after precipitation, which is related to the removal of minor amounts of oligomers and cyclic compounds (91% yield after precipitation, see also GPC traces in Figure ). Similar increases of molecular weight for polythioethers after drying have been reported in literature . Figure (left side) also depicts the 1 H‐NMR spectrum of P1c .…”

“…Similar increases of molecular weight for polythioethers after drying have been reported in literature. [27] Figure 2 (left side) also depicts the 1 H-NMR spectrum of P1c. Methylene groups a adjacent to the ether bond can be discerned as triplet at a chemical shift of 3.38 ppm.…”

Thiol‐Ene Cationic and Radical Reactions: Cyclization, Step‐Growth, and Concurrent Polymerizations for Thioacetal and Thioether Units

“…Recently, Tew and Sarapas reported the synthesis of functional poly(thioether)s, by radical step‐growth polymerizations between a functional dithiol and divinyl ether, and their application as lithium polymer electrolytes . In addition, various thiols and vinyl ethers have been subjected to radical step‐growth polymerizations for other applications .…”

Utilizing thiol–ene chemistry for crosslinked nickel cation‐based anion exchange membranes

“…One polymerization technique that has the potential to accomplish those goals is the photo‐induced thiol–ene reaction. This reaction has gained attention for its fast reaction times, high conversions, ambient reaction conditions, and high functional group tolerance . The thiol–ene reaction has been used extensively to produce crosslinked networks in a controlled and efficient manner, simply by incorporating monomers with more than two degrees of functionality .…”

“…This reaction has gained attention for its fast reaction times, high conversions, ambient reaction conditions, and high functional group tolerance. [42][43][44][45][46][47][48][49] The thiol-ene reaction has been used extensively to produce crosslinked networks in a controlled and efficient manner, simply by incorporating monomers with more than two degrees of functionality. 42,43,45,50,51 In addition, functional polymers have been synthesized and used in the thiol-ene reaction, allowing for greater control of membrane properties, dependent on the polymers incorporated.…”