An in situ FTIR study of undoped PolyBenzoImadazole as a function of relative humidity

Undoped, cast films of PolyBenzoImadazole (PBI) were investigated as a function of humidity using both H2O and D2O, and as a function of temperature up to 100 °C in order to better understand the infrared response of this polymer, as well as to provide benchmark data for subsequent studies on acid doped PBI. Marked changes across the mid-IR range were observed during the uptake of water and D2O. The use of D2O proved extremely useful in terms of deconvoluting the complex IR response observed and allowed the IR data to be rationalised in terms of the disruption of the N-H … N inter-chain hydrogen bonded network and changes in the morphology of the polymer.