Malfait Benjamin, Pouessel Alban, Jani Aîcha, Morineau Denis
Institute of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes, France.
J Phys Chem Lett. 2020 Jul 16;11(14):5763-5769. doi: 10.1021/acs.jpclett.0c01564. Epub 2020 Jul 7.
This work investigates the phase behavior of aqueous solutions of glycerol confined in MCM-41 and SBA-15 nanoporous matrixes by calorimetry. Limitations due to overfilling and eutectic freezing are prevented by the absence of an external liquid reservoir and by the glass-forming property of glycerol. Consequently, the stability of nanoconfined ice in equilibrium with aqueous solutions is studied over a wide range of compositions. In confinement, a large temperature depression of the liquidus line is observed. A thermodynamic model accounting simultaneously for the cryoscopic and the Gibbs-Thomson effects gives a consistent view of the phase diagram for large pores ( = 4.15 nm). For smaller pores ( = 1.8 nm), it reveals that the water activity strongly deviates from the bulk solution with the same composition, indicating the possible role of concentration heterogeneities in determining the onset of ice freezing in strongly nanoconfined solutions.
本研究通过量热法研究了限制在MCM - 41和SBA - 15纳米多孔基质中的甘油水溶液的相行为。由于不存在外部液体储器以及甘油的玻璃形成特性，避免了因过填充和共晶冻结导致的限制。因此，研究了在广泛组成范围内与水溶液处于平衡状态的纳米限域冰的稳定性。在受限情况下，观察到液相线有较大的温度降低。一个同时考虑冰点降低效应和吉布斯 - 汤姆逊效应的热力学模型，对大孔（ = 4.15纳米）的相图给出了一致的观点。对于较小的孔（ = 1.8纳米），结果表明水活度与相同组成的本体溶液有很大偏差，这表明浓度不均匀性在确定强纳米限域溶液中冰冻结起始方面可能发挥的作用。
