Fatemeh Shokrolahi - Polyurethane Department, Iran Polymer and Petrochemical Institute, Tehran,Iran.
Hamid Yeganeh - Polyurethane Department, Iran Polymer and Petrochemical Institute, Tehran,Iran.
Hamid Mirzadeh - Department of Polymer Engineering, Amirkabir University of Technology, Tehran, Iran.

Segmental long bone defects are healed with autogenous bone graft which often results morbidity of the donor site. So, existence of biodegradable bone graft substitutes to facilitatebone regeneration in critical size defects is necessary. For this purpose, poly (urethane urea)s are an ideal class of materialsbecause of their biocompatibility, good mechanical properties. Recently, we reported the preparation of thermoplasticsegmented poly (urethane urea)s (PUU) based on polycaprolactone (PCL) through an one-pot system for bone tissue engineering applications with high mechanicalproperties and low degradation rate[1]. It is well documented that the degradation rate of PUU can be modified through the selection of soft segment. In the present study partial substitution of PCL with a hydrophilic polyethylenglycol (PEG) was considered as a means of controlling the hydrolyticdegradation rate of PUUs. [2] Since, calcification is a required property in bone tissue engineering [3] calcification of PUUs was investigated