Characterization of poly(ethylene glycol)-b-poly(ε-caprolactone) by liquid chromatography under critical conditions: Influence of catalysts and reaction conditions on product composition

Amphiphilic block copolymers were synthesised by ring opening polymerization of ε-caprolactone with polyethylene glycol monomethyl ether (PEG-MME) using different catalysts (boron trifluoride, sodium hydride, and tin octoate) in a one pot procedure. The products obtained were characterized with respect to their molar mass distribution and content of homopolymers using size exclusion chromatography (SEC), Liquid chromatography under critical conditions (LCCC) and MALDI-TOF–MS. The homopolymers of caprolactone could be separated from the block copolymer by LCCC on a reversed phase column in tetrahydrofurane–water mobile phases with evaporative light scattering detection (ELSD). Residual monomer could be determined under the same conditions using density detection, a separation of the copolymer from residual initiator could be achieved on a normal phase column in acetone–water mobile phases.