Hello everyone, please help me.
Recently, I am making cyclic oligomers of Poly(1,4-cyclohexylenedimethylene terephthalate), and the oligomers are only soluble in Trifluoroacetic acid while the polymer can be dissolved in Chloroform. I tried to explain this phenomenon by Hansen solubility parameters, but it seems impossible. The difference in the Hansen solubility parameters of polymer and oligomers is not much. My supervisor suggested explaining by density, rigid structure of oligomers, but I can not find any references to this ideal.
Could anyone have experience in this field or there any good literature recommendation?
Thank you very much, and have a nice day.
Dear Dieu Minh Ngo, you have to consider the compactness (reflected by density) of both. Solubility among many parameters it depends on the diffusability of the solvent molecules. Please tell the solubility parameters of the two solvents, oligomer and polymer, in addition to densities of these two laters. My Regards
There is only one influential factor: the solubility parameter of your oligomer and of your solvent, they need to match; the window for solubility parameter difference allowing to make true solutions will be the smaller, the higher the molecular weight of your oligomer.
(please be careful to differentiate betewen true solutions and colloidal dispersions, which look the same by eye if well done, but are totally different, like plus and minus, like day and night)
Abdelkader BOUAZIZ Bernhard Wessling
Firstly, I very appreciate your answers.
I calculated the solubility of cyclic oligomer/polymer by Small's and Fedors's methods with molar attraction constants and molar volumegiving δ=12.04 for both cyclic oligomer/polymer. For solvents, Chloroform has δD=17.8, δP=3.1, δH=5.7; Trifluoroacetic acid has δD=15.6, δP=9.9, δH=11.6 as I refer from "Hansen solubility parameters A user's handbook - Charles M.Hansen.
I got the Mw of my cyclic oligomer less than 2000m/z by Maldi-TOF, and I think the polymer and Chloroform can make a true solution because that is the way I separate cyclic oligomer and remaining polymer after reaction, and Chloroform is the solvent I used to analyse the polymer by NMR.
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