Gresh-Sill M, Banerjee S, Meyer TY, Velankar SS. Salt Effects on the Phase Behavior and Cocrystallization Kinetics of POCB-Water Mixtures.
LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024;
40:2862-2871. [PMID:
38306462 PMCID:
PMC10867884 DOI:
10.1021/acs.langmuir.3c02428]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 01/02/2024] [Accepted: 01/05/2024] [Indexed: 02/04/2024]
Abstract
Mixtures of water with polyoxacyclobutane (POCB) have a unique phase diagram which combines liquid-liquid equilibrium (LLE) at high temperatures and cocrystallization of a POCB-hydrate at low temperatures. Such cocrystal hydrate formation is extremely rare among polymers. We report on the effects of adding NaCl salt on the phase behavior of POCB-water mixtures and the kinetics of hydrate crystallization from such mixtures. Salt loadings of less than 0.1 wt % were found to greatly expand the LLE region. Salt loadings of ∼10 wt % were found to significantly decrease the melting temperature of the hydrate below its ∼37 °C value under salt-free conditions. The hydrate was found to be remarkably tolerant of salt and persists at room temperature even when equilibrated with salt-saturated water. Salt was found to slow down hydrate crystallization, and the degree of slowing was greater than that expected from the salt-induced decrease in undercooling due to melting point depression.
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