Compatibility of polypeptide blends of poly(γ-butyl glutamate)/poly(γ-benzyl glutamate)

The compatibility of poly(γ-butyl glutamate)/poly(γ-benzyl glutamate) blend was examined by the estimation of the side chain dispersion of polypeptides in terms of the condition of preparation of blend films and the blend ratio. The polypeptide blend prepared for very short casting time exhibited an apparent compatibility. On the other hand, the polypeptide blend cast for long time did show incompatibility, irrespective of the blend ratio or mole fraction. The structures of the separated phase changed around mole fraction of 0.5 with the increasing mole fraction. The poly(γ-butyl glutamate) island phase transformed into the poly(γ-benzyl glutamate) island phase with increasing mole fraction of poly(γ-benzyl glutamate) according to the calculation of the simple island-matrix model by Takayanagi et al.