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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/25

Title: Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose- Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation
Authors: Patra, Animesh
Verma, Pramod K
Mitra, Rajib K
Issue Date: 2012
Publisher: J. Phys. Chem. B
Citation: A. Patra, P. K. Verma and R. K. Mitra, Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose-Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation, J. Phys. Chem. B, 2012, 116, 1508-1516
Abstract: In this study, we have explored the slow (of the order of several hundreds of picoseconds) relaxation dynamics of water associated with the hydration shell of a biocompatible polymer, hydroxypropyl cellulose (HPC)-water mixture as a function of HPC concentration using time-resolved fluorescence spectroscopy. The relaxation dynamics slows down with a progressive increase in HPC content indicating restriction of the relaxation pathway of water molecules specially beyond a cellulose concentration of 20% wherein an isotropic to liquid crystalline cholesteric microscopic phase separation sets in. The activation energy calculated from the temperature dependent solvation dynamics studies also shows a similar trend. The nucleophilic activity of water molecules in these mixtures is determined by measuring the reaction kinetics of solvolysis of benzoyl chloride, and the reaction rate exhibits a marked decrease as the phase separation sets in. The observed results are correlated with a transition between the ‘bulk’ and ‘bound’ type of water molecules present in the system.
URI: http://hdl.handle.net/123456789/25
Appears in Collections:2012

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