The relative molecular masses of the amphiphilic diblock copolymers(methoxy poly(ethylene glycol))-poly(ε-caprolactone)(MeOPEG-PCL) and(methoxy poly(ethylene glycol))-poly(ε-caprolactone-co-d,l-lactide)(MeOPEG-P(CL-co-LA)) were determined by ~1H NMR and GPC,respectively,and the ratios of LA units to CL units in MeOPEG-P(CL-co-LA) copolymer were also determined by ~1H NMR.The relative molecular masses obtained by ~1H NMR in different deuterated solvents were nearly identical,and were close to the theoretical...