H. Komber, S. Chakraborty, B. Voit
Apr 3, 2012
Citations
1
Influential Citations
17
Citations
Journal
Polymer
Abstract
Abstract Commercial polyethersulfone (Udel ® 1800) based on 4,4′-dihydroxy-2,2-diphenylpropane (bisphenol-A) and dichlorodiphenylsulfone was post-sulfonated using trimethylsilyl chlorosulfonate under mild conditions. The partially sulfonated polyethersulfones were investigated by 1 H and 13 C NMR in their acid and/or sodium salt form. Several 13 C NMR signals could be assigned up to the triad level. 13 C- T 1 relaxation times were determined by the inversion recovery method for all carbons to ensure conditions for quantitative 13 C NMR measurements. Additionally, the nuclear Overhauser enhancements are given. The degree of sulfonation (DS) of the samples covers the range from 13.6 to 100% as determined both by 1 H and 13 C NMR spectroscopy. The NMR spectra confirm that the sulfonation occurs solely as mono-substitution of each phenyl ring of the dioxy-2,2-diphenylpropane unit in ortho -position to the ether bond. The microstructure of all polymers was evaluated from the content of dioxy-2,2-diphenylpropane-based diads and diphenylsulfone-centred triads. From the development of non-, mono- and disulfonated dioxy-2,2-diphenylpropane units with increasing DS it can be concluded that the sulfonation of the first phenyl ring retards the sulfonation of the second one. Thus, the non-sulfonated units deplete faster and the monosulfonated units are enriched compared with a random sulfonation. There is no reactivity influence between dioxy-2,2-diphenylpropane units which are separated by a diphenylsulfone unit because the content of diphenylsulfone-centred units follows the random distribution.