Phase Separation in Aqueous Solutions of Polyethylaminophosphazene Hydrochloride during Heating

作者：Grinberg V Ya^*; Grinberg N V; Burova T V; Dubovik A S; Tur D R; Papkov V S

来源：Polymer Science - Series A, 2010, 52(11): 1220-1227.

DOI：10.1134/S0965545X10110167

It is shown that aqueous solutions of polyethylaminophosphazene hydrochloride undergo phase separation during heating. This phenomenon is studied in detail at pH 3.5 (0.1 M citrate buffer) in relation to the composition of the system with the use of nephelometry and high-sensitivity DSC. The cloud points and the enthalpy of phase separation of the system are determined, and its phase diagram is constructed. The system features a lower critical solution temperature: w(2,cr) = 7.3 x 10(-4) and T-cr = 34.3 degrees C. The enthalpy of phase separation is 12.8 +/- 0.6 J/g of the polymer, regardless of the system composition. A new approach to the analysis of DSC data on the phase separation of aqueous solutions of polymers during heating is advanced on the basis of calorimetric parameters coupled with the data on the composition of coexisting phases. Through this approach, the main contribution to the heat effect of phase separation of the system under study is related to a change in the energy state of a polyethylaminophosphazene hydrochloride molecule as a result of its dehydration.

• 出版日期2010-11