Poly(p-phenylene)s tethered with oligo(ethylene oxide): synthesis by Yamamoto polymerization and properties as solid polymer electrolytes

Abstract

rsc.li/polymers Poly( p-phenylene)s tethered with oligo(ethylene oxide): synthesis by Yamamoto polymerization and properties as solid polymer electrolytes † Hannes Nederstedt and Patric Jannasch * Salt-containing supramolecular assemblies of rigid-rod polymers tethered with flexible ion-solvating side chains represent a synthetic pathway towards thin ion-conducting solid electrolyte membranes with high dimensional stability. In the present work we have synthesized poly( p-phenylene)s (PpPs) carrying di-, triand tetra(ethylene oxide) side chains, respectively. p-Dichlorophenyl oligo(ethylene oxide) monomers were polymerized by Ni-mediated Yamamoto polymerization via in situ reduction of Ni(II). This gave PpPs with an average degree of polymerization reaching 60, where each phenylene ring carried one oligo (ethylene oxide) side chain. Results from calorimetry and X-ray scattering measurements clearly showed the formation of molecular composites, i.e., bicontinuous morphologies with mechanically reinforcing layers of the stiff PpP backbones separated by the flexible oligo(ethylene oxide) side chains. This morphology was retained after adding lithium bis(trifluoromethane)sulfonimide (LiTFSI) to form salt-inpolymer electrolytes, but with an increased distance between adjacent backbones. Furthermore, upon addition of salt the order-to-disorder transition (ODT) region increased from ∼50-170°C to ∼75-200°C at [EO]/[Li] = 20. Increasing salt concentrations also revealed a maximum in the ODT enthalpy at [EO]/[Li] = 40. At 80 and 160°C, the ionic conductivity reached 1.1 × 10 −4 and 1.0 × 10 −3 S cm −1 , respectively. Finally, we demonstrate that ionic conductivity of the polymer electrolytes can be significantly increased by additions of triglyme. † Electronic supplementary information (ESI) available: 13 C and HMQC NMR spectra of P( pP-EO 3 ), molar mass distributions of the polymers, additional thermal data for neat polymers and electrolyte membranes, photographs of P( pP-EO 2 ) films, frequency dependence of the ionic conductivity of the P( pP-EO 3 )-30 membrane. See

Li‐Salt Doped Single‐Ion Conducting Polymer Electrolytes for Lithium Battery Application

“…To circumvent this strategies of blending, copolymerization, and addition of traditional liquid battery solvents, such as propylene carbonate (PC), have been applied. [8,16,18,19] For example Nederstedt et al [20,21] prepared an LiPSTFSI-PEO block copolymer SICs and reached ionic conductivities of 10 -4 -10 -7 S cm -1 at 80 °C; Ma et al [10] obtained ≈10 -4 S cm -1 at 90 °C for an LiPSTFSI/PEO blend; Feng et al [17] created an LiPSTFSI-based copolymer reaching 10 -4 S cm -1 at 90 °C; and Bouchet et al [22] prepared an LiP-STFSI/PEO tri-block copolymer with >10 -5 S cm -1 at 60 °C. Beaudoin et al [23] also prepared an LiPSTFSI-PEO-LiPSTFSI tri-block copolymer with >10 -5 S cm -1 at 60 °C.…”

Synthesis, Phase Structure, and Ion Conductivity of Poly(p-phenylene) Functionalized with Lithium Trifluoromethanesulfonimide and Tetra(ethylene Oxide) Side Chains

“…The synthesis of p PCl 2 -EO 4 is described in detail elsewhere . In brief, the synthesis began with tosylation of tetra­(ethylene glycol) monomethyl ether using sodium hydroxide as a base in a two-phase system of water and THF.…”

“…The polymerization was carried out by following a modified, previously reported method (Scheme c) . The copolymers were designated as P X where X refers to the molar ratio between EO and Li + ions in the product.…”

“…Recently, we exploited Yamamoto coupling to prepare homopolymers consisting of poly­( p -phenylene) backbones in which each phenylene ring was tethered with an oligo­(EO) side chain containing 2, 3, or 4 EO units, respectively. Subsequently, a selection of these polymers was doped with lithium bis­(trifluoromethane)­sulfonimide (LiTFSI) salt . These polymer electrolytes formed molecular composite morphologies with ionic conductivities reaching 10 –4 S cm –1 at 80 °C.…”

Functional polymers for lithium metal batteries

“…Systematic analysis of the effect of polymer architecture on the conductivity revealed that the macromonomer and BASPs with equivalent Li salt loading had comparable ability of dissociating Li salts. Recently, a Yamamoto homocoupling reaction has been exploited to polymerize 2,5-dichlorophenolic monomers functionalized with short PEO chains [108] . The self-assembly of p -phenylene backbones resulted in stacked structures with phase separated soft EO domains, and their morphology was preserved upon addition of Li salt.…”