Systems composed of poly(ethylene)glycol
(PEG 400) + water + either
potassium carbonate or sodium carbonate were studied at 283.15, 298.15,
and 313.15 K. The effects of temperature and the electrolyte on phase
segregation were evaluated. The phase segregation process was endothermic
and entropically driven. The efficacy of the cations in inducing phase
formation with PEG 400 followed the order K2CO3 < Na2CO3. The binodal curves were successfully
described using the empirical equation suggested by Merchuk and modified
to include the effect of temperature. Tie-line compositions were correlated
using the Othmer–Tobias, Bancroft, and Hand equations. The
experimental tie-line data for PEG 400 + K2CO3 + water and PEG 400 + Na2CO3 + water were
also correlated using the nonrandom two liquid model. The use of this
thermodynamic model resulted in reliable data for the system while
reducing the number of experiments needed. All of the correlations
indicated satisfactory fits between the calculated and experimental
data.
A wide
characterization of the phase equilibrium involved in aqueous
biphasic micellar systems (ABMSs) formed by 10,000 or 35,000 g mol–1 polyethylene glycol (PEG) + t-octylphenoxypolyethoxyethanol
(Triton X-100) + water was evaluated at 283.15, 298.15, and 313.15
K, respectively. The influences of temperature, polymer molar mass,
and mixture compositions on the phase diagrams obtained were evaluated.
The analysis of the phase diagrams obtained experimentally showed
that the increase of temperature favors, significantly, the phase
separation process. The increase in the polymer molecular weight from
10,000 to 35,000 g mol–1 has an even more pronounced
effect than that of temperature in inducing phase separation. The
experimental liquid–liquid equilibrium (LLE) data were then
theoretically correlated using the extended Flory–Huggins lattice
model for ternary mixtures. The interaction parameters of the component’s
pairs PEG–Triton X-100 (λ12), PEG–water
(λ13), and Triton X-100–water (λ23) in the ABMSs were estimated at different temperatures and
in two different surfactant configurations (single molecule and micellar
aggregates). Although it was not possible to correlate the parameters
of interaction with the physical reality of ABMSs, the Flory–Huggins
model allowed to recover the LLE data within the experimental error
range. The experimental data of the binodal curves for the different
ABMSs were also adjusted through the Othmer–Tobias, Bancroft,
and Setschenow empirical equations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.