Comparison of Temperature Effects on the Salting Out of Poly(ethylene glycol) versus Poly(ethylene oxide)−Poly(propylene oxide) Random Copolymer

Abstract

In common with many poly(ethylene glycol)s (PEGs), a poly(ethylene oxide)−poly(propylene oxide) random copolymer (EO−PO, with EO/PO = 1:1.3) of molecular weight 3320 g·mol−1, known as Sunbright-3320 (SB-3320), can be salted out of aqueous solution using kosmotropic salts such as (NH4)2SO4 to form aqueous biphasic systems (ABSs) comprising upper polymer-rich and lower salt-rich aqueous phases. The effects of temperature on these liquid/liquid ABSs and related solid/liquid resin-based systems, where one end of the polymer has been covalently attached to a solid support, have been studied. Distribution ratios of NH4 99TcO4 were determined radiometrically at various polymer and salt concentrations and temperatures. SB-3320-grafted poly(styrene) resins exhibit opposite effects of variable-temperature partitioning compared to the SB-3320-based ABS. However, the results are complicated because of the conformational changes that are possible for the SB-3320 polymer. Enthalpy and entropy changes were found to be temperature-dependent. The differences observed between the distribution of 99TcO4 − in EO−PO-based systems versus PEG-based systems can be attributed to the lower cloud point temperatures and probable conformational changes for the EO−PO systems.

N,N-Diallylglycidylamine: A Key Monomer for Amino-Functional Poly(ethylene glycol) Architectures

“…PEG and its copolymers are known to exhibit lower critical solution temperature (LCST) behavior in water (Figure ). ,− ,− The LCSTs found were in the range of 29–94 °C, depending on the amount of the apolar DAGA monomer in the chain (cf. Table ).…”

Probing the stability of sterically stabilized polystyrene particles by centrifugal sedimentation

“…Effect of electrolyte addition. It has been shown previously via various techniques, including cloud point measurements, [29][30][31] rheology, 32,33 and NMR, 34 that the solvency of poly(ethylene glycol) (PEG) chains in water can be compromised by the addition of electrolyte. The addition of electrolyte has two effects on the PEG polymeric chains; rstly it disrupts the hydrogen bonding between the ether groups and water molecules and secondly it binds to the PEG thus screening the weak electrostatics induced by the ion-dipole interactions around the oxygen atoms on the polymer chains.…”

Valorisation of red beet waste: one-step extraction and separation of betalains and chlorophylls using thermoreversible aqueous biphasic systems

“…Therefore, the studied ABS follows an LCST-type behaviour, being a direct consequence of the PPG-water binary system LCST-type behaviour. 30 Since PPG-a temperature-dependent polymer-increases its hydrophobic character with temperature, it is more readily displaced from the IL into a second, increasingly polymer-enriched phase.…”