Acidity of the methyne group of poly(4-vinylpyridine) leads to side-chain protonation in pyridine

Poly(4-vinylpyridine) swollen in pyridine displays changes in electrical conductivity in response to white light and to low level thermal perturbation; protonation of the side-chain nitrogen is believed to play a role. Here we present spectroscopic evidence that the proton donor is the methyne group CH on the polymer chain.