Microphase Separation and High Ionic Conductivity at High Temperatures of Lithium Salt-Doped Amphiphilic Alternating Copolymer Brush with Rigid Side Chains

Abstract

An amphiphilic alternating copolymer brush (AACPB), poly{(styrene-g-poly(ethylene oxide))-alt-(maleimide-g-poly{2,5-bis[(4methoxyphenyl)oxycarbonyl]styrene})}(P{(St-g-PEO)-alt-(MI-g-PMPCS)}), was synthesized by alternating copolymerization of styreneterminated poly(ethylene oxide) (St-PEO) and maleimide-terminated poly{2,5-bis[(4-methoxyphenyl)-oxycarbonyl]styrene} (MI-PMPCS) macromonomers using the "grafting through" strategy. 1 H NMR and gel permeation chromatography coupled with multiangle laser light scattering were used to determine the molecular characteristics of AACPBs. Although these AACPBs cannot microphase separate with thermal and solvent annealing methods, they can form lamellar structures by doping a lithium salt. This is a first report on lithium salt-induced microphase separation of AACPBs, and the lithium salt-doped AACPBs can serve as solid electrolytes for the transport of lithium ion. For the same AACPB, the ionic conductivity (σ) increases with increasing doping ratio. In addition, σ values of different AACPBs with the same doping ratio become higher for shorter PMPCS side chains. The σ value of the lithium salt-doped AACPB increases with increasing temperature in the range of 25−240 °C, and σ is 1.79 × 10 −4 S/cm at 240 °C. The relatively high σ values of the lithium-doped AACPBs at high temperatures benefit from the rigid PMPCS side chain and the AACPB architecture. The lithium salt-doped AACPBs have the potential to serve as solid electrolytes in high-temperature lithium ion batteries.

Solid Polymer Electrolytes with High Conductivity and Transference Number of Li Ions for Li‐Based Rechargeable Batteries

“…[ 108 ] Copolymers and grafted polymers are self‐assembling compounds forming ion‐conducting chains acting as Li + transport channels. [ 109 ] A list of possible branched SPEs is quite diverse because of the numerous possible combinations of backbones and branching chains, as well as polymer cores. Phosphates, boron‐containing compounds, polyhedral oligomeric silsesquioxane, and even organic nanoparticles, have all been utilized as cores.…”

Styrene‐Maleimide/Maleic Anhydride Alternating Copolymers: Recent Advances and Future Perspectives

“…Alternating copolymerization of styrene‐terminated poly(ethylene oxide) (S‐PEO) and maleimide‐terminated poly(2,5‐bis((4‐methoxyphenyl)‐oxycarbonyl)styrene) (MI‐PMPCS), macromonomers via grafting‐through strategy produced an amphiphilic alternating copolymer brush ( Figure ). [ 121 ] After being doped with a lithium salt, the copolymer can form lamellar structures, microphase separation, and can serve as a solid electrolyte for lithium‐ion transportation. The ionic conductivity of the same copolymer brush can be increased by increasing the doping ratio.…”

“…In addition, the copolymers form unique nanostructure morphologies which have applications in the industry [ 110,111 ] and in the field of nanotechnology. [ 120,121 ] Apart from these, the copolymers are used in biomedical science due to their excellent delivery [ 90,92 ] and release systems for drugs and genetic materials. [ 93,95 ] The copolymers also produce special architectures which are used in environmental science for toxic metal removal, [ 106,107 ] contaminated dye separation, [ 101,102 ] and producing new kinds of coating materials.…”

Patterning Polyelectrolyte Complexes with Alternating Monomer Sequence Distributions

“…23 At the molecular level, alternating styrene/maleimide systems have increased chain stiffness 24 and can be easily modified to link pendant groups to the main chain for nonlinear optics, 25,26 supramolecular materials, 27 fluorimetric sensing 28 or polymer electrolytes. 29 However, to the extent of our knowledge, there are no examples to date of bringing this strategy to synthetic designer polyelectrolytes to modulate the physical state of polyelectrolyte complexation.…”