Hydrogen Bonding in Polymers: Effect of Temperature on the OH Stretching Bands of Poly(vinylphenol)

A detailed analysis of the bands appearing in the OH stretching region of the infrared spectrum of poly(vinylphenol) and their changes with temperature is presented. Bands usually assigned to "free" (nonhydrogen-bonded) groups contain overlapping contributions from both monomeric and end-group species, both hydrogen-bonded to 7 orbitals. Assignments of bands due to hydrogen-bonded groups are made on the basis of whether the proton and oxygen in a particular OH group are both involved in hydrogen bonds (as "donors" and "acceptors", respectively) or whether one or the other is "free" (not hydrogen-bonded). The assignment of other modes is more uncertain, and various possibilities are discussed. Changes in absorption coefficient with temperature appear to affect bands due to hydrogen-bonded groups in the interior of chains and monomeric species by essentially the same amount. The large change in absorption coefficient of the hydrogen-bonded band relative to a band assigned to free groups postulated in a previous study is more likely due to a change in the distribution of hydrogen-bonded and "free" species that were not resolved in previous work.