Studies of Ion Conductance in Polymers Derived from Norbornene Imidazolium Salts Containing Ethyleneoxy Moieties

Abstract

“Two-armed” imidazolium polymers 2a–2f, most of which contain oxyethylene moieties as linkers and ethyleneoxy terminal units, were prepared via ROMP. These polymers were thermally stable, with 5% weight losses occurring at 350 ± 5 °C under nitrogen. Their glass transitions were −22 to −51 °C, mostly ∼3 °C higher than those of the respective monomers. The conductivities of the polymers were 4–30-fold lower than those of the respective monomers. The maximum room temperature (RT) conductivity, σ25 = 2.27 × 10–5 S/cm, was observed with the polymer 2f with a tetra­(oxyethylene) linker (X = 4) and a terminal di­(ethyleneoxy) unit (Y = 2). Reduction of the double bonds in polymers 2 resulted in only small changes in T g of the resultant 3 but 2.4-fold loss in RT conductivities. Four “one-armed” norbornene imidazolium TFSI monomers via ROMP produced polymers 5, whose T gs were generally low (−50 to −65 °C) and very close to those of the monomers. Although the RT conductivities were reduced by about an order of magnitude from the monomers, the polymers with tetra­(oxyethylene) linkers (X = 4) and di- and triethyleneoxy terminal units (Y = 2 or 3) (5c and 5d) had σ25 ∼ 3 × 10–5 S/cm, similar to the best two-armed polymer. Two ABA triblock copolymers 8 were successfully synthesized from norbornene-N-phenylimide and two-armed monomers with different terminal ethyleneoxy units (1d and 1e); these polymers demonstrated single direction actuation, but their performance was mediocre because of phase mixing that prevented the formation of the required bicontinuous phase morphology.

The Effect of Oligo(oxyethylene) Moieties on Ion Conduction and Dielectric Properties of Norbornene-Based Imidazolium Tf2N Ionic Liquid Monomers

“…Recently, we reported a series of new imidazolium-based norbornene diester ILMs having double imidazolium (= Im + ) (CF 3 SO 2 ) 2 N – (= Tf 2 N – ) (termed Im + Tf 2 N – ) arms as pendants containing either alkylene [(CH 2 ) 2 ] or oxyethylene [(OCH 2 CH 2 ) x = (OE) x , x = 1, 2 or 3] units as linkers between the norbornene moiety and the imidazolium cation and their PILs, via ring-opening metathesis polymerization (ROMP). , Although there have been a few studies of PILs based on single-arm polynorbornenes for self-healing materials , and conducting polymer electrolytes, − the conduction mechanism in norbornene-based ILMs and PILs with double-arm geometries is far from being fully understood. The focus of the current investigation is therefore to explore molecular parameters that control the ionic conductivity of norbornene double imidazolium-based ILMs, while a full report on the dynamics of the corresponding PILs will comprise a forthcoming publication.…”

Role of Chain Polarity on Ion and Polymer Dynamics: Molecular Volume-Based Analysis of the Dielectric Constant for Polymerized Norbornene-Based Ionic Liquids

“…From the norbornene-based Im + Tf 2 N – ILMs, the PILs with two- or one-armed imidazolium pendant structures, containing alkylene or oxyethylene moieties as linkers and ethyleneoxy terminal units, were synthesized via ring-opening metathesis polymerization (ROMP) Figure shows the chemical structures of four norbornene Im + Tf 2 N – ROMP PILs [termed P_D (or S)_C 2 OE x ImEO y , where P = polymer, D = double, S = single, C 2 = (CH 2 ) 2 , OE = oxyethylene, Im = imidazolium, and EO = ethyleneoxy].…”

“…In our accompanying publication, the ionic conduction and dielectric response of norbornene-based Im + -Tf 2 N – ILMs were thoroughly investigated, and this study demonstrated a significant effect of linker polarity (alkylene vs oxyethylene) between the norbornene and Im + moieties on the ionic conductivity, glass transition temperature, and dielectric constant. The focus of the present paper is to explore ionic and segmental dynamics of polymers synthesized from those norbornene ionic liquid monomers via ring-opening metathesis polymerization (ROMP) . The ROMP approach provided a narrow gap between norbornene-based ILM and PIL T g values (only 3–7 °C differences), a big advantage of using ROMP PILs for single-ion conducting polymers.…”

“…The focus of the present paper is to explore ionic and segmental dynamics of polymers synthesized from those norbornene ionic liquid monomers via ring-opening metathesis polymerization (ROMP) . The ROMP approach provided a narrow gap between norbornene-based ILM and PIL T g values (only 3–7 °C differences), a big advantage of using ROMP PILs for single-ion conducting polymers. It is known that ionic conductivity in single-ion conducting polymers (so-called ionomers) depends on the charge concentration and mobility (or diffusion coefficient) of the ionic species participating in ion conduction. ,,− Those physical quantities are controlled directly by polarity of the medium ,, and glass transition temperature ( T g ); ,, i.e., lowering T g results in a faster segmental motion, thus boosting counterion mobility, while increasing polarity leads to decreased ion aggregation, allowing more ions to take part in conduction.…”

Diastereoselective Opening of Bridged Anhydrides by Amidoximes Providing Access to 1,2,4‐Oxadiazole/Norborna(e)ne Hybrids

“…The corresponding structural profile can be desired for some medicinal targets such as GPR40 . Furthermore, this scaffold can be easily modified via carboxylic group functionalization and C=C double bond transformation, including enantioselective cyclopropanation, and metathesis polymerization …”