Light scattering and viscosity studies on poly‐4‐vinylpyridine

Seven fractionated and three unfractionated samples of poly‐4‐vinylpyridine, ranging in molecular weight from about 7 × 10 4 to 2 × 10 6 , were investigated by light scattering and viscosity studies at 25°C. Intrinsic viscosity‐molecular weight relationships in 86:14 butanone‐isopropanol and in 92.01 weight per cent ethanol were [η] = 3.80 × 10 −4 M 0.57 and [η] = 1.20 × 10 −4 M 0.73 , respectively. Flory's constant K , defined by the relation [η]θ = KM 0.5 , was determined by two independent methods to be 8.1 × 10 −4 . The close agreement of this value with that obtained for polystyrene confirms Flory's hypothesis that the unperturbed molecular dimensions are controlled by steric effects. The relationship between molecular dimensions and second virial coefficient is in fair agreement with recently proposed theoretical relations. The negative temperature coefficient of the solubility of poly‐4‐vinylpyridine in tert ‐butanol‐benzene mixtures indicates strong solvation through hydrogen bonding between pyridine and hydroxyl groups.