Hydrophilic Block Azidation of PCL‐b‐PEO Block Copolymers from Epichlorohydrin

Abstract

Abstract Amphiphilic diblock copolymers poly( ϵ ‐caprolactone)‐ b ‐poly(ethylene oxide) (PCL‐ b ‐PEO) with well‐controlled pendant azido groups along the hydrophilic PEO block, that is, poly( ϵ ‐caprolactone)‐ b ‐poly(ethylene oxide‐ co ‐glycidyl azide) (PCL‐ b ‐P(EO‐ co ‐GA)), are synthesized from poly( ϵ ‐caprolactone)‐ b ‐poly(ethylene oxide‐ co ‐epichlorohydrin) (PCL‐ b ‐P(EO‐ co ‐ECH)). The further conversion of those azido groups along the hydrophilic block of copolymers into amino or carboxyl groups via click chemistry is studied. The micelles self‐assembled from PCL‐ b ‐P(EO‐ co ‐GA) with azido groups on the shell are crosslinked by the dialkynyl‐PEO. The micelles with crosslinked shell show better stability, higher drug loading capacities, subsequent faster drug release rate, and higher cytotoxicity to cancer cells. The introduction of azido groups into PCL‐ b ‐PEO amphiphilic diblock copolymers from epichlorohydrin in PEO hydrophilic block in this work provides a new method for biofunctionalization of micelles via mild click chemistry.