Microstructural analysis of PLGA-PEG-PLGA copolymer based on NMR spectroscopy using model compounds.

This study presents a novel strategy for studying the microstructure of PLGA-PEG-PLGA triblock copolymers synthesized via the ROP mechanism using various organic catalysts. The use of model copolymers (PLG-PEG-PLG, PLA-PEG-PLA) and multidimensional NMR spectroscopy (HSQC, HMBC, DOSY) enabled a more comprehensive characterization of the structure of PLGA-PEG-PLGA copolymers. The new method was verified by comparing the average molecular weights with the reference method-gel permeation chromatography. NMR analysis demonstrated a close correlation between the type of catalyst used, the monomer sequence arrangement, and the average molecular weights. The Zn(acac)₂ and Fe(acac)₃ catalysts demonstrated similar activity to the commonly used Sn(Oct)₂, making them potential substitutes in the synthesis of PLGA-PEG-PLGA copolymers. The proposed methodology provides detailed insight into copolymer microstructure, enabling more precise design of copolymers, which is essential for optimizing drug delivery systems.