Dear Abdelkader, thank you for the article you recommended, but my polymer is different from normal PLGA-PEG polymer. It is amine terminated and this modification changes the solubility of the polymer or there is another problem :(
Dear Hamide, end groups didn't contribute that much to solubilty. What is working against solubilty is the high crystallization ability and tendency of PGLA fragment of the diblock copolymer. My Regards