Chemoenzymatic synthesis of the novel amphiphilic diblock copolymer poly[caprolactone-block-(glycidyl methacrylate)] from a bifunctional initiator and its micellization behavior

摘要

The chemoenzymatic synthesis of a novel diblock copolymer consisting of a hydrocarbon block of polycaprolactone (PCL) and an epoxy-based block of poly(glycidyl methacrylate) (PGMA) was achieved by the combination of enzymatic ring-opening polymerization (eROP) and atom transfer radical polymerization (ATRP). A trichloromethyl-terminated PCL macrointiator was obtained via Novozyme 435-catalyzcd eROP of e-caprolactone from a bifunctional initiator, 2,2,2-trichloroethanol, under anhydrous conditions. PCL-b-PGMA diblock copolymers were synthesized in a subsequent ATRP of glycidyl methacrylate. The kinetics analysis of ATRP indicated a 'living'/controfled radical polymerization. The macromolecular structure and thermal properties of the PCL macroinitiator and of the diblock copolymer were characterized using NMR spectroscopy, gel permeation chromatography and differential scanning calorimetry. The well-defined PCL-b-PGMA amphiphilic diblock copolymer self-assembled in aqueous solution into nanoscale micelles. The size and shape of the resulting micelles were investigated using dynamic light scattering, transmission electron microscopy and tapping-mode atomic force microscopy. (C) 2007 Society of Chemical Industry.