I am trying to understand the Flory-Huggins theory and calculate the solubility interaction parameter via the group contribution method, but I am unable to get the values of certain functional groups.

What I understand is, all i need is the interaction values for each functional group, if i add them and put in the Hildebrand equation i will get the desired value.

I can get my hands on DSC and TGA values of gliclazide, but unfortunately i don't have the molecular modelling software.