Salt effect on gel permeation chromatography of partially charged polymers

The effect of the addition of 0.1M LiBr to dimethylformamide (DMF) solutions of charged and uncharged polymers has been studied by GPC and [η] measurements. LiBr has a salting‐out effect on polyacrylonitrile (with (PAN‐S) and without (PAN) sulfonate sulfur), polystyrene (PS), and poly(vinyl acetate) (PVAc), which is seen by a decrease in [η] and an increase in the GPC retention time. The increase in retention time is, however, abnormally high for charged polymers. Association in PAN and PAN‐S solutions in DMF can explain the experimental observations.