Diffusion, viscosity and sedimentation of poly(ethylene oxide) in water

Chew, Benjamin G. M.; Couper, A.

doi:10.1039/f19767200382

Cited by 17 publications

(8 citation statements)

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“…X‐ray structural analysis has shown that crystalline PEG chains can adopt two extreme structural conformations: a zigzag, random coil structure for shorter chains, or a winding, helical structure for longer chains 49. It has been argued from earlier studies that viscosity50–53 and diffusion coefficient data50 support a random coil conformation, whereas it has been claimed from calorimetric data54 that it adopts a helical conformation. Based on volumetric studies, Lepori and Mollica32 favour a compromise model for PEG in solution is a hydrated flexible coiled polymer with some helical segments.…”

Section: Resultsmentioning

confidence: 99%

Effect of PEGylation on the Solution Conformation of Antibody Fragments

Harding

Turner

et al. 2008

Journal of Pharmaceutical Sciences

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Section: Resultsmentioning

confidence: 99%

Effect of PEGylation on the Solution Conformation of Antibody Fragments

Harding

Turner

et al. 2008

Journal of Pharmaceutical Sciences

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“…Increasing temperature decreases the magnitude of both the excess partial molar enthalpy and entropy of PEG in solution (Figure 7), and suggests that the structure of the hydration shell around the PEG gradually disappears as the temperature is raised. That is, the decrease in magnitude of the partial molar entropy of PEG in solution as temperature increases can be attributed to the increase in the free rotation of chain links and weakening of the polymersolvent interactions in solution (Chew and Couper, 1976). On the other hand, increasing temperature does not significantly change either the excess partial molar enthalpy or entropy of DEX (Figure 8).…”

Section: Discussionmentioning

confidence: 97%

Effect of temperature on the phase equilibrium of aqueous two‐phase polymer systems

et al. 1993

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We report experimental data showing the effect of temperature on polymer partitioning in the dextran (DEX500) -polyethylene glycol (PEG8000) -water system. Increasing temperature increases the concentration of PEG in the top phase and decreases the concentration of DEX in the bottom phase. A solution thermodynamic model based on local compositions with temperature-dependent parameters correlates the experimental data well, and an efficient Gibbs-free energy minimization algorithm for phase equilibrium calculations is described. The partial molar enthalpies and entropies of each of the solutes, calculated with the model, are negative and decrease in magnitude as temperature increases.

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“…This result can be compared with the end to end distance calculated from where C ∞ is the so-called characteristic ratio, which is a measure of the effect of short-range interactions within a chain, n is the number of bonds, and l is the average C−C bond length of 0.146 nm in PEO and PPO . For PEO in water, C ∞ (PEO) ≅ 5 …”

Section: Discussionmentioning

confidence: 99%

“…46 For PEO in water, C ∞ (PEO) = 5. 51 Experimental values of C ∞ (PPO) for PPO in water are not available since PPO is not water soluble. However, in various polar solvents C ∞ (PPO) = C ∞ (PEO).…”

Section: Discussionmentioning

confidence: 99%

H NMR Relaxation Studies of the Micellization of a Poly(ethylene oxide)−Poly(propylene oxide)−Poly(ethylene oxide) Triblock Copolymer in Aqueous Solution

1996

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1H nuclear magnetic resonance (NMR) relaxation studies of the temperature-induced micellization of a poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide), PEO−PPO−PEO, block copolymer in aqueous solution were performed in the range 280−345 K. 1H NMR spectra of the block copolymer were well resolved, thus allowing us to probe specifically the methyl and methylene relaxation processes in the PPO and PEO blocks, respectively. Interpretation of the relaxation data in terms of the Hall−Helfand correlation function leads to four distinct correlation times for the PPO and PEO blocks. The slower correlation time in the PPO block was identified as the Zimm−Rouse first normal mode of the copolymer and served to determine the hydrodynamic radius, R H, of the unimers and the micelles. On a more local scale, the behavior of the correlation time for segmental motions in the PPO block indicates an extension of the PPO chains in micelles relative to the unimers. This conformational change is related to the formation of a water insoluble liquid-like core created by the PPO chains in the micelle where the trans isomers are favored. The rotational isomeric states model used to interpret the faster correlation time in the PEO chains yields an activation energy of 14.6 kJ/mol for the correlated transitions in the PEO blocks, in agreement with previous theoretical calculations. The slower correlation time in the PEO blocks shows a marked increase upon micellization attributed in part to the polymer−polymer interactions between the different PEO blocks constituting the hydrophilic moiety of the micelles. A power law relating this relaxation time to the micelle hydrodynamic radius is predicted and observed experimentally. The concentration dependence of the critical micellization temperature, inferred from the methyl spin−lattice relaxation time in the PPO block, was found to be adequately described by a closed association model. The standard free energy, enthalpy, and entropy of micellization obtained by NMR are in close agreement with the recent experimental thermodynamic studies of P. Alexandridis et al. (Macromolecules 1994, 27, 2414).

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Diffusion, viscosity and sedimentation of poly(ethylene oxide) in water

Cited by 17 publications

References 0 publications

Effect of PEGylation on the Solution Conformation of Antibody Fragments

Effect of PEGylation on the Solution Conformation of Antibody Fragments

Effect of temperature on the phase equilibrium of aqueous two‐phase polymer systems

H NMR Relaxation Studies of the Micellization of a Poly(ethylene oxide)−Poly(propylene oxide)−Poly(ethylene oxide) Triblock Copolymer in Aqueous Solution

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