PLGA‐( L ‐Asp‐ alt ‐diol) x ‐PLGAs with Different Contents of Pendant Amino Groups: Synthesis and Characterization

Summary: A series of novel biodegradable multi‐block copolymers PLGA‐( L ‐Asp‐ alt ‐diol) x ‐PLGA with pendant amino groups was synthesized by ring‐opening polymerization of D , L ‐lactide/glycolide( D,L‐ LA/GA) (75/25) using poly( N ‐Cbz‐ L ‐Asp‐ alt ‐diol)s as macroinitiator and stannous octoate as catalyst, in which the N ‐Cbz‐ L ‐Asp represents N ‐carbobenzyloxy‐ L ‐aspartic acid and diols are ethylene glycol, triethylene glycol, PEG200, and PEG600, respectively. Their structures and properties were characterized by FTIR, 1 H NMR, DSC, GPC, and elemental analysis (EA). The contents of the L ‐Asp unit in the copolymers were increased from 12.9 to 79.3 mmol · g −1 with decreasing the chain length of the diol, while the glass transition temperatures of the copolymers were decreased from 27.1 to 11.7 °C with increasing the chain length of the diol. Thus, the results in this study provide a way to prepare biomaterials with different L ‐Asp unit densities or different number of bioactive sites as well as different properties through adjusting the chain length of the diol.Synthesis of PLGA‐( N ‐Cbz‐ L ‐Asp‐ alt ‐diol) x ‐PLGA copolymers.