Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (pluronic)/poly(epsilon-caprolactone) (PCL) amphiphilic block copolymeric nanospheres- I. Preparation and characterization

Amphiphilic block copolymers based on PEO-PPO-PEO block copolymer (Pluronic ) and poly(epsilon-caprolactone) were synthesized by bulk polymerization. T he structural analysis of Pluronic/PCL block copolymer was carried out usin g FT-IR, H-1 NMR, GPC, WAXD, DSC and TGA measurements. To prepare copolymer ic nanospheres with a micellar structure, Pluronic/PCL amphiphilic block co polymers were dialyzed against water. The size and size distribution of Plu ronic/PCL block copolymeric nanospheres were examined by dynamic light scat tering measurement. They showed an average diameter of 116 to 196 nm depend ing on the type of copolymer. All the nanosphere samples exhibited a narrow size distribution. The critical micelle concentrations of Pluronic/PCL amp hiphilic block copolymers determined by fluorescence spectroscopy were lowe r than that of common low molecular weight surfactants. We confirmed the fo rmation of stable copolymeric nanospheres through the solution behavior of amphiphilic block copolymer in selective solvents. (C) 1999 Elsevier Scienc e B.V. All rights reserved.