Phase behaviour of poly(N-vinyl caprolactam) in water

The solution behaviour of the system poly(N-vinyl caprolactam)/water has be en studied. Experiments and theoretical calculations indicate a typical Flo ry-Huggins (Type I) demixing behaviour with a lower critical solution tempe rature (LCST). The critical concentration and LCST shift to lower values wi th increasing molar mass of the polymer. The phenomenological description o f such a system predicts a continuous temperature controlled swelling behav iour of the corresponding network. A comparison with literature data confir ms this prediction. A calorimetric study of the crystallisation and melting behaviour of water and the concentration dependence of the glass transition temperature, gives no evidence for the formation of a polymer/solvent complex. (C) 2000 Elsev ier Science Ltd. All rights reserved.