Intramolecular hydrogen bond analysis in liquid polymers studied by FT-IR spectroscopy

Infrared (IR) absorption measurements on Propylene glycol (PG) and its oligomers Poly (propylene glycols) (PPG_s) with different molecular weights (M.W. 425, 725, and 4000 Da) performed in the O-H stretching region are presented. The goal is to study the intramolecular H-bond imposed band as well as to assign the various sub-bands in terms of the different aggregates present, so clarifying the dynamical response of this complex class of associated systems in this particular and interesting region. The observed experimental data, compared with that of previous IR measurements on other similar polymers, ethylene glycol (EC) and poly (ethylene glycols) (PEG_s) confirm the role played by the H-bond in the structural environments of these liquinds, being discussed on the basis of current theories for associated systems.