Predictions of bound water content in poly(N-isopropylacrylamide) gel

The bound water content (BWC) in a poly(N-isopropylacrylamide) gel throughout the volume transition is predicted using the extended lattice-fluid hydrogen-bond theory. The calculations indicate that the bound water content in the gel is about 0.4 g/g at temperature above LCST, whereas the free water content below LCST is least 3-4 time greater that the bound water content. The theoretical predictions compare well with the reported DSC data. It is also shown that the polymer H static line width measurements in NMR can give BWC, which in agreement with the reported DSC data and theoretical predictions.