Fourier transform infrared and dielectric study of water–C12E4 liquid crystals

Abstract

Fourier transform infrared (FT-IR) spectroscopy and time domain reflectometry (TDR) have been employed to study nano-confinement effects in water–tetraethylene glycol monododecyl ether (C12E4) system as a function of the water to surfactant molar ratio (R) at 25 °C. The study emphasises that, at low R values, the vibrational dynamics of water entrapped between equidistant parallel bilayers of oriented surfactant molecules is significantly different from that of pure water whereas at R>7 it becomes practically indistinguishable. On the other hand, even at the higher R values investigated, the dielectric properties of the aqueous domain confined in water–C12E4 liquid crystals are found to be strongly affected by confinement effects. The observed single relaxation processes with a symmetrical distribution of relaxation time are discussed in terms of effects due to interfacial interactions and topological restrictions on water-surfactant head group dynamics in liquid crystals. Correlation between the structural and dynamical properties of water–C12E4 liquid crystals and thermal effects due to microwave irradiation on these highly viscous microheterogeneous systems are also discussed.