TY  - JOUR
AU  - van der Loop, T.H.
AU  - Panman, M.R.
AU  - Lotze, S.
AU  - Zhang, J.
AU  - Vad, T.
AU  - Bakker, H.J.
AU  - Sager, W.F.C.
AU  - Woutersen, S.
TI  - Structure and dynamics of water in nonionic reverse micelles: A combined time-resolved infrared and small angle x-ray scattering study
JO  - The journal of chemical physics
VL  - 137
SN  - 0021-9606
CY  - Melville, NY
PB  - American Institute of Physics
M1  - PreJuSER-22197
SP  - 044503
PY  - 2012
N1  - The authors would like to thank Stichting voor Fundamenteel Onderzoek der Materie (FOM) for financial support and Dr. P. Konarev (EMBL-Hamburg) for assistance in performing the SAXS experiments.
AB  - We study the structure and reorientation dynamics of nanometer-sized water droplets inside nonionic reverse micelles (water/Igepal-CO-520/cyclohexane) with time-resolved mid-infrared pump-probe spectroscopy and small angle x-ray scattering. In the time-resolved experiments, we probe the vibrational and orientational dynamics of the O-D bonds of dilute HDO:H(2)O mixtures in Igepal reverse micelles as a function of temperature and micelle size. We find that even small micelles contain a large fraction of water that reorients at the same rate as water in the bulk, which indicates that the polyethylene oxide chains of the surfactant do not penetrate into the water volume. We also observe that the confinement affects the reorientation dynamics of only the first hydration layer. From the temperature dependent surface-water dynamics, we estimate an activation enthalpy for reorientation of 45 ± 9 kJ mol(-1) (11 ± 2 kcal mol(-1)), which is close to the activation energy of the reorientation of water molecules in ice.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:22852627
UR  - <Go to ISI:>//WOS:000307611500038
DO  - DOI:10.1063/1.4736562
UR  - https://juser.fz-juelich.de/record/22197
ER  -