The hydrophobic TPU grade Tecoflex TM EG72D and the hydrophilic TPU grades Tecophilic TM SP60D60, SP93A100 and TG2000 were obtained from Merquinsa (a Lubrizol Company, Ohio, USA). As shown in Fig. 1, the hard segment (HS) of the hydrophobic and hydrophilic TPUs is a combination of hexamethylene diisocyanate (HMDI) and 1,4-butanediol (i.e. chain extender).
Although the hydrophobic and hydrophilic TPUs have a similar hard segment, the chemical composition of the soft segment (SS) is different. The soft segment of Tecophilic TM is PEO (polyethylene oxide), while the soft segment of Tecoflex TM is polytetrahydrofuran (pTHF).
4615
Metformin.HCl was purchased from Fagron (Waregem, Belgium).
Verstraete G., Mertens P., Grymonpré W., Van Bockstal P.J., De Beer T., Boone M.N., Van Hoorebeke L., Remon J.P, & Vervaet C. (2016). A comparative study between melt granulation/compression and hot melt extrusion/injection molding for the manufacturing of oral sustained release thermoplastic polyurethane matrices. International journal of pharmaceutics, 513(1-2).