Anomalous conformational behavior of short poly(oxyethylene) chains in water: An FT-IR spectroscopic study

Abstract

Conformational behavior of short poly oxyethylene) (POE) chains in water has been studied by FT-IR spectroscopy. The spectra of aqueous solutions of CH 3(OCH 2CH 2) m OCH 3 with m = 2–6 were measured for various concentrations by using a horizontal ATR accessory. The observed spectra show that, with increasing water fraction, the population of the gauche conformation about the OCCO bond increases, but the direction of the conformational preference is reversed for lower concentrations. The observed maximum of the gauche population is interpreted as a consequence of anomalous enhancement of the gauche population in a specific concentration region. This effect is more significant for shorter POE chains. These observations suggest that there exist some specific interactions, which highly favor the gauche conformation of the OCH 2CH 2O segment, for limited composition regions of the binary systems of short POE chains and water.