ct,co-Diaminopropyl terminated polycyanopropyl methylsiloxane-polyurea is studied by high resolution 1H n.m.r. In concentrated dimethylformamide (DMF) solution, there are no hydrogen bonds between polyurea and DMF, and between polyurea and water. Hence, solvent effects can be ignored. There are several NH reasonances in the IH n.m.r, spectra. The different chemical shifts are due to different types of hydrogen bonds. At higher temperatures, hydrogen bonding of the NH groups is not dissociated, and the relative amounts of each NH peak remain the same in the temperature range 23-82°C. The chemical shift changes of the NH group forming hydrogen bonds are greater than those of free NH with increasing temperature. The morphology of the polyurea chain in concentrated DMF solution appears to be similar to that in the solid state from the two-dimensional NOESY spectrum.
Посилання на статтю:
Molecular interactions in polyurea by 1-D and 2-D n.m.r. / Xingjun Lu*, Yuanshen Wang and Xuewen Wu // Polymer. – 1993. – Vol 34. – P. 56-60.