Formulation and Characterization of TPU

Medical grade TPU, Elastollan^® supplied by BASF (Lemförde, Germany), was received in raw pellets form. It is a polyether based TPU with polytetramethylene oxide (PTMO) as SS, 4,4-diphenylmethane diisocyanate (4,4-MDI) as HS and 1,4-butane diol (1,4-BDO) as a chain extender. Tetrahydrofuran (THF) of HPLC grade (≥99.8%) was supplied by Honeywell Riedel-de HaënTM (Seelze, Germany). Sodium Carbonate (Na₂CO₃) and salt tablets for Phosphate Buffer Solution (PBS) preparation were supplied by Sigma Aldrich (Steinheim, Germany). Ethanol of HPLC grade (≥99.9%) was supplied by Fisher Chemical (Geel, Belgium).