Reduced mobility of di-propylene glycol methylether in its aqueous mixtures by quasielastic neutron scattering.
نویسندگان
چکیده
The hydrogen (H-) bonding interplay between water and other organic molecules is important both in nature and in a wide range of technological applications. Structural relaxation and, thus, diffusion in aqueous mixtures are generally dependent on both the strength and the structure of the H-bonds. To investigate diffusion in H-bonding mixtures, we present a quasielastic neutron scattering study of di-propylene glycol methylether (2PGME) mixed with H(2)O (or D(2)O) over the concentration range 0-90 wt.% water. We observe a nonmonotonic behavior of the dynamics with a maximum in average relaxation time for the mixture with 30 wt.% water, which is more than a factor 2 larger compared to that of either of the pure constituents. This is a result in qualitative agreement with previous calorimetric studies and the behavior of aqueous mixtures of simple mono-alcohols. More surprisingly, we notice that the dynamics of the 2PGME molecules in the mixture is slowed down by more than a factor 3 at 30 wt.% water but that the water dynamics indicates an almost monotonous behavior. Furthermore, in the low momentum transfer (Q) range of the 2PGME, where the intermediate scattering function I(Q,t) is considerably stretched in time (i.e., the stretching parameter β ≪ 1), it is evident for the 2PGME-D(2)O samples that the Q-dependence of the inverse average relaxation time, <τ>(-1), is greater than 2. This implies that the relaxation dynamics is partly homogenously stretched, i.e., the relaxation of each relaxing unit is somewhat intrinsically stretched in time.
منابع مشابه
Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering.
The molecular dynamics of solutions of di-propylene glycol methylether (2PGME) and H2O (or D2O) confined in 28 Å pores of MCM-41 have been studied by quasielastic neutron scattering and differential scanning calorimetry over the concentration range 0-90 wt.% water. This system is of particular interest due to its pronounced non-monotonic concentration dependent dynamics of 2PGME in the correspo...
متن کاملStudy of Surface Tension of Binary Mixtures of Poly (Ethylene Glycol) in Water and Poly (Propylene Glycol) in Ethanol and its Modeling Using Neural Network
متن کامل
Thermodynamic Study of Copper Sulphate and Zinc Sulphate in Water and Binary Aqueous Mixtures of Propylene Glycol
Partial molar volumes of copper sulphate and zinc sulphate have been determined in water and binary aqueous mixtures of propylene glycol (2,4,6 and 8% by weight of propylene glycol) at 303.15 K with the help of density measurements. Effect of temperature on the partial molar volumes was also analysed for these salts in water and binary aqueous mixtures of propylene glycol. Results obtained have...
متن کاملRheology and Structure of Cornstarch Suspensions in Water-Poly(propylene glycol) Mixtures
Concentrated aqueous cornstarch (CS) suspensions are often used to demonstrate an extreme example of shear thickening rheological behaviour. Here, we describe the increased rheological complexity that occurs on the addition of poly(propylene glycol) 10 (PPG) to an aqueous CS suspension. The appearance of shear thickening/jamming, shear thinning, yield stress and near-Newtonian behaviours is dep...
متن کاملHydration of cement: The application of quasielastic and inelastic neutron scattering
Quasielastic and inelastic neutron scattering have been highlighted as excellent tools for studying the hydration of cement components. Here, the complimentary application of inelastic and time-resolved quasielastic neutron scattering to investigate the reaction kinetics during the crucial first 24 h of hydration will be highlighted. Some recent results include the interaction of tricalcium and...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of chemical physics
دوره 133 23 شماره
صفحات -
تاریخ انتشار 2010