Supercooled glucose

Figure 3.2 shows the mean square displacement (MSD) for water in the glassy and supercooled glucose solutions in a log-log scale. The most remarkable result is that water diffuses at 220 K, in the glass, as observed in the experiments. The diffusion at 220 K, however, occurs in a scale comparable with the /rs of the simulation and cannot be quantified from the data in Figure 3.2. For the five supercooled solutions, T = 250 to 365 K, we computed the diffusion coefficient from the long time dependence of...

Molinero, V., Cagin, T., and Goddard III, W.A. The mechanisms of nonexponential relaxation in supercooled glucose solutions The role of water facilitation, /. Phys. Ghent., 108, 3699, 2004. 

FIG. 1S-2. Storage shear modulus of supercooled glucose, from data of Philippoff - and Meyer and Ferry reduced to 55°C. Dashed curve represents behavior of a single Maxwell element with parameters given in the text. 

Mean square displacement of water in 12%wt water-glucose in the supercooled and glass regime. The dotted line corresponds to 3.5 A, comparable with the diameter of a water molecule. 

Nonexponential parameter p of the translational relaxation of water (upper panel) and glucose (lower panel) in the viscous supercooled liquid at temperatures from 1.5Tg (365 K), through 1.4Tg (335 K), to 1.3Tg (310 K). Note that for each temperature, water relaxation is more nonexponential (lower p) than for glucose. The p parameters were obtained from the stretched exponential fit of the intermediate scattering function Fs(k,t) for each component. 

Translational Diffusion of Water in Supercooled 12%wt Water Glucose... 

We did not find any evidence of free volume channels in the mixtures of water and glucose, consistent with previous results of a study for water-sucrose in a broader range of water content (Molinero et al., 2003). The existence of such charmels, and the role of free volume in the dynamics of mixtures of oligosaccahrides with a high degree of polymerization deserve further study. The results presented here for water relaxation in supercooled DP12 allows us to generalize the observed mechanism for water diffusion in... 

The dielectric behaviour of viscous molecular liquids has been studied since the early 1930 s. Baker and Smyth (48) had observed relaxation in supercooled isoamyl- and isobutyl bromide in the kHz region and had noted the similarity to the relaxations of liquid glucose (49) and glycerol (50). Similar... 

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