Structural Evolution of a Polystyrene-Block-Poly(Ethylene Oxide) Block Copolymer in Tetrahydrofuran/Water Cosolvents

Abstract

This study aims to quantitatively investigate the effect of water content on the self-assembly behavior of polystyreneblock-poly(ethylene oxide) (PS-b-PEO) in tetrahydrofuran/water cosolvents by small-angle X-ray scattering. PS-b-PEO chains preferentially form fractal aggregates at a dilute concentration in neat tetrahydrofuran (THF). By adding a small amount of water into THF, PS-b-PEO forms gelled networks. The gelled networks have correlated inhomogeneities, which were generated through mesophase separation. These gelled networks are not present when PS-b-PEO is dissolved in THF/methanol and THF/ethanol cosolvents. The substitution of water with 12 M HCl reduces the viscosity of the gelled networks. Those results indicate that the gelled networks of PS-b-PEO need hydrogen bonds formed from surrounding water molecules to be bridging agents, which connect different PEO block chains together. Upon increasing the water content in THF/water cosolvents, dispersed micelles with a core− shell conformation or aggregated micelles preferentially coexist with fractal aggregates.

A Review of Polymer‐based Solid‐State Electrolytes for Lithium‐Metal Batteries: Structure, Kinetic, Interface Stability, and Application

“…The PEO derivatives with block copolymers have raised special attention because they not only improve lithium salt dissociation and ionic conductivity, but also take advantage of microphase separation to balance the two antagonistic properties of ion transport and mechanical stiffness [22,23] . Nanostructured block copolymer electrolytes (BCE) have a promising applications in polymer electrolyte design, such as polystyrene‐ block ‐poly(ethylene oxide) (SEO) with the polystyrene block offering mechanical stiffness, and the PEO block solvates lithium salt and derived ions transport from lithium bis(trifluoromethansulfonyl)imide (LiTFSI) [24] .…”

“…However, there are two main issues for PEO-based electrolytes: 1) the strong ionic bond À CÀ OÀ coordinated in the PEO chains between O atom and lithium ions restrict the ionic conductivity (< 10 À 7 S cm À 1 ) and lithium-ion transference number at room temperature; 2) higher glass transition temperature, resulting in high crystallinity at room temperature, which limits the movement of chain segments; 3) the limited electrochemical window stability below 4 V. The PEO derivatives with block copolymers have raised special attention because they not only improve lithium salt dissociation and ionic conductivity, but also take advantage of microphase separation to balance the two antagonistic properties of ion transport and mechanical stiffness. [22,23] Nanostructured block copolymer electrolytes (BCE) have a promising applications in polymer electrolyte design, such as polystyreneblock-poly(ethylene oxide) (SEO) with the polystyrene block offering mechanical stiffness, and the PEO block solvates lithium salt and derived ions transport from lithium bis(trifluoromethansulfonyl)imide (LiTFSI). [24] Danie et al prepared polystyrene-block-poly(ethylene oxide) (SEOÀ LiTFSI) and PEOÀ LiTFSI for experimental analysis to quantify the conductivity and ion dynamic transport mechanism in PEO-based bulk copolymer electrolyte.…”

Formation of Self-Healing Granular Eutectogels through Jammed Carbopol Microgels in Supercooled Deep Eutectic Solvent

“…Note that the Carbopol microgel is transparent under the optical microscope, indicating that most of the swollen microgel contains water. As a result, both Mie and Rayleigh scattering are not significant. − Despite their similar appearance, a quantitative comparison is necessary to assess their similarity. Figure c illustrates the quantitative comparison between the two aforementioned samples through UV–vis analysis.…”

Programmable Compartment Networks by Unraveling the Stress‐Dependent Deformation of Polymer Vesicles

“…In the dispersion of polymer vesicles, organic solvent (THF: dioxane = 4:1 v/v) and water form a homogenous mixture by forming hydrogen bonds with each other, which is denoted as solvent molecules in subsequent force analysis. [ 28 ] The Hildebrands solubility parameter (δ) of the mixed solvent with 50.0 vol% water is ≈33.6 MPa 1/2 , which is much higher than that of polystyrene (δ = 19.2 MPa 1/2 ). The vesicular membrane has a poor permeability for the solvent molecules, which collide with the membrane due to thermal motion and generate force perpendicular to the membrane.…”