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Redox-Responsive Block Copolymers: Poly(vinylferrocene)‑b‑poly(lactide) Diblock and Miktoarm Star Polymers and Their Behavior in Solution

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journal contribution
posted on 28.10.2013, 00:00 by Jan Morsbach, Adrian Natalello, Johannes Elbert, Svenja Winzen, Anja Kroeger, Holger Frey, Markus Gallei
The synthesis of diblock and miktoarm star polymers containing poly­(vinylferrocene) (PVFc) and poly­(l-lactide) (PLA) blocks is introduced. End functionalization of PVFc was carried out via end capping of living carbanionic PVFc chains with benzyl glycidyl ether (BGE). By hydrogenolysis of the benzyl protecting group a dihydroxyl end-functionalized PVFc was obtained. Both monohydroxyl- and dihydroxyl-functionalized PVFcs have been utilized as macroinitiators for the subsequent polymerization of l-lactide via catalytic ring-opening polymerization. A series of block copolymers and AB2 miktoarm star polymers was synthesized with varied PLA chain lengths. All polymers were characterized in detail, using 1H NMR spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF). The molecular weight of the block copolymers and AB2 miktoarm star polymers are in the range of 8000–15000, containing a PVFc block of weight 7800. In addition, the self-assembly behavior of the polymers in dichloromethane (CH2Cl2) was investigated by using dynamic light scattering (DLS) and transmission electron microscopy (TEM). In a selective solvent for PLA the block copolymers and miktoarm star polymers formed vesicle-like structures with different diameters.