A mixture made of alpha-cyclodextrin, 4-methylpyridine and water was recently reported to undergo an inverse melting/freezing phenomenon. The physical origin of this counterintuitive process is still a debated issue; nevertheless, the interplay of structural and dynamic features seems a key point in solving the apparent thermodynamic paradox. We investigated the dynamics of this mixture in a wide range of temperature, concentration and wavevector by time-resolved transient grating spectroscopy. We found that in the lower temperature region of the phase diagram the mixture shows clear evidence of a viscoelastic effect and a slowing-down phenomenon. These dynamic features suggest the presence of a glass transition at low temperature.
Low-temperature supercooled phase of α-cyclodextrin:4-methylpyridine:water mixture / M. PLAZANET; P. BARTOLINI; A. TASCHIN ; R. TORRE. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - STAMPA. - 19:(2007), pp. 205108(1)-205108(8). [10.1088/0953-8984/19/20/205108]
Low-temperature supercooled phase of α-cyclodextrin:4-methylpyridine:water mixture
BARTOLINI, PAOLO;TASCHIN, ANDREA;TORRE, RENATO
2007
Abstract
A mixture made of alpha-cyclodextrin, 4-methylpyridine and water was recently reported to undergo an inverse melting/freezing phenomenon. The physical origin of this counterintuitive process is still a debated issue; nevertheless, the interplay of structural and dynamic features seems a key point in solving the apparent thermodynamic paradox. We investigated the dynamics of this mixture in a wide range of temperature, concentration and wavevector by time-resolved transient grating spectroscopy. We found that in the lower temperature region of the phase diagram the mixture shows clear evidence of a viscoelastic effect and a slowing-down phenomenon. These dynamic features suggest the presence of a glass transition at low temperature.File | Dimensione | Formato | |
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