Naslov
Evolution of the micro-structure of aqueous alcohol mixtures with cooling: A computer simulation study

Autori
Požar, Martina ; Perera, Aurélien.

Izvornik
Journal of molecular liquids (0167-7322) 248 (2017), Supplement C; 602-609

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
computer-simulations, aqueous-ethanol, aqueous-tbutanol, temperature-dependence

Sažetak
We study by computer simulations aqueous ethanol and tert-butanol mixtures for temperatures below room temperature, from T=250 K to T=150 K, in order to monitor how concentration fluctuations and micro-segregation evolve with the lowering of temperature. Similarly to our recent study of aqueous-methanol mixtures [J. Chem. Phys. 145, 144502 (2016)], we find that concentration fluctuations tend to decrease - as monitored by the lowering of the k = 0 value of the structure factors, while micro-segregation becomes more specific, in particular with a marked tendency of water to form short chain-like clusters, instead of large bulky nano-domains at higher temperatures. This clustering translates into a growing pre-peak in the water-water structure factors at k ≈ 0.5Å −1. The decrease of concentration fluctuations is also in agreement with the fact that calculated Kirkwood-Buff integrals tend to become ideal, in sharp contrast with the data for T=300 K, in particular for aqueous-tbutanol mixtures. This near-ideality is a consequence of water forming supra-molecular linear clusters. We conjecture that the cooling of nano-structured mixtures produces a “transfer” of k = 0 concentration fluctuation mode towards k≠0 mode, leading in particular to these supra-molecular water clusters.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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