Propylene Oxide Segments Research Articles

Promote the conductivity of solid polymer electrolyte at room temperature by constructing a dual range ionic conduction path

Poly(ethylene oxide) (PEO) is a classic matrix model for solid polymer electrolyte which can not only dissociate lithium-ions (Li+), but also can conduct Li+ through segmental motion in long-range. However, the crystal aggregation state of PEO restricts the conduction of Li+ especially at room temperature. In this work, an amorphous polymer electrolyte with ethylene oxide (EO) and propylene oxide (PO) block structure (B-PEG@DMC) synthesized by the transesterification is firstly obtained, showing an ionic conductivity value of 1.1 × 10−5 S/cm at room temperature (25 °C). According to the molecular dynamics (MD) simulation, the PO segments would lead to an inconsecutive and hampered conduction of Li+, which is not beneficial to the short range conduction of Li+. Thus the effect of transformation of aggregation state on the improvement of ionic conductivity is not enough, it is necessary to further consider the different coupled behaviours of EO and PO segments with Li+. In this way, we blend this amorphous polymer (B-PEG@DMC) with PEO to obtain a dual range ionic conductive solid polymer electrolyte (D-SPE) with further improved ionic conductivity promoted by constructing a dual range fast ionic conduction, which eventually shows a further improved ionic conductivity value of 2.3 × 10−5 S/cm at room temperature.

Effects of temperature and concentration on the structure of ethylene oxide–propylene oxide–ethylene oxide triblock copolymer (Pluronic P65) in aqueous solution: a molecular dynamics simulation study

The effects of temperature and solution concentration on the structure of triblock polymeric surfactant (ethylene oxide)19(propylene oxide)29(ethylene oxide)19 (Pluronic P65) have been investigated by fully atomistic molecular dynamics simulations. The Flory–Huggins interaction parameter χ, hydrogen bonding and molecular mobility in the aqueous solution of P65 were investigated covering a composition range of 0.1–0.73 (water weight fraction) and a temperature range of 273–373 K. The Flory–Huggins parameters indicated that propylene oxide (PO) segments became hydrophobic with the increase in temperature, whereas ethylene oxide (EO) segments remained hydrophilic, which caused the increase in repulsion between EO and PO segments. The intermolecular hydrogen bonds in P65 solution including water–water hydrogen bonds and water–P65 hydrogen bonds increased with the increase in solution concentration and decreased with the increase in temperature. The critical micellar temperature of Pluronic P65 predicted by Flory–Huggins interaction parameter χ and hydrogen bonding was in good agreement with experimental data.

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

The adsorption thermodynamics of copolymers, based on ethylene oxide (EO) and propylene oxide (PO) units, at the laponite (RD) clay/liquid interface was determined at 298 K. The copolymer nature was tuned at molecular level by changing the hydrophilicity, the architecture and the molecular weight (Mw) keeping constant the EO/PO ratio. Polyethylene (PEGs) and polypropylene (PPGs) glycols with varying Mw and their mixture were also investigated to discriminate the role of the EO and the PO segments in the adsorption process. Enthalpies of transfer of RD, at fixed concentration, from water to the aqueous macromolecule solutions as functions of the macromolecule molality were determined. They were treated quantitatively by means of a model based on two equilibria: (1) one-to-one binding between the macromolecule and the site on the solid and (2) two-to-one binding following which one macromolecule interacts with another one adsorbed onto the solid. The good agreement between the equilibrium constants obtained from calorimetry and those determined from kinetic experiments confirmed the reliability of the experimental and theoretical approaches. Almost all of the systems investigated are highlighted by the one-to-one binding; the L35 and 10R5 systems present both equilibria. The insights provided by the thermodynamics of adsorption of their homopolymers onto RD were fruitful in obtaining detailed information on the nature of the forces involved between RD and the copolymers. The data obtained in the present work clearly evidenced that for comparable polymer Mw, PPG is more suitable in building up a steric barrier around the RD particles and, indeed, exhibits several advantages and no drawbacks. Moreover, the parent copolymers may properly functionalize the RD surface by exploiting both their high affinity to the solid surface and the ability to self-assemble onto it as L35 and 10R5 clearly showed.

SANS Investigation of Polyether Block Copolymer Micelle Structure in Mixed Solvents of Water and Formamide, Ethanol, or Glycerol

The solution structure of a representative polyether block copolymer (Pluronic P105: EO37PO58EO37, where EO and PO denote ethylene oxide and propylene oxide segments, respectively) has been invest...

Infrared spectroscopic investigations of the adsorption of ethylene oxide–propylene oxide copolymers from CCl4on pyrogenic silica

The adsorption of statistic and block copolymers of ethylene oxide (EO) and propylene oxide (PO) and of corresponding homopolymers on silica (Aerosil 200) from CCl4 and CHCl3 was investigated by IR spectroscopy. The adsorption isotherms were determined from the concentration difference in the solution, and the fraction of adhered segments from the IR absorption of free and hydrogen-bonded SiOH groups. Competition and displacement studies demonstrate that the EO segments are preferentially adsorbed compared with the PO segments. The fraction of adhered segments decreases with increasing amount adsorbed, molar mass, EO fraction and blocklength. The dependences are interpreted by conformational models of the block copolymers with central PO or EO blocks.