The temperature dependence of the peculiar behaviour of poly(N-vinyl-2-pyrrolidone) in water. Specific effect or conformational transition?

Intrinsic viscosity [η], measurements in water at different temperatures were carried out for one fraction of poly(vinylpyrrolidone) (PVP). An anomalous behaviour of [η] at 30°C is observed. The shape of the plot of [η] vs T seems to indicate that PVP undergoes a peculiar change in water. Values of the partial specific compressibility (LC) for PVP at various temperatures are compared with the intrinsic viscosity results. This anomalous behaviour of [17], can be interpreted in terms of the different amount of hydration and the break of water structure with temperature obtained through the LC values for PVP as function of temperature.