Phase separation in aqueous solutions of polyethylaminophosphazene hydrochloride during heating |
| |
Authors: | V Ya Grinberg N V Grinberg T V Burova A S Dubovik D R Tur V S Papkov |
| |
Institution: | 1.Emanuel Institute of Biochemical Physics,Russian Academy of Sciences,Moscow,Russia;2.Nesmeyanov Institute of Organoelement Compounds,Russian Academy of Sciences,Moscow,Russia |
| |
Abstract: | 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 × 10−4 and T
cr = 34.3°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. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|