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Synthesis and Direct Visualization of Dumbbell-Shaped Molecular Brushes

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journal contribution
posted on 17.01.2012, 00:00 by Ang Li, Zhou Li, Shiyi Zhang, Guorong Sun, Danielle M. Policarpio, Karen L. Wooley
Dumbbell-shaped triblock molecular brushes were synthesized by ring-opening metathesis polymerization (ROMP) of poly­(lactide) macromonomers with terminal norbornene groups (NB-PLA) in a sequential addition manner. By changing the macromonomer size and the feed ratio of Grubbs’ catalyst to macromonomer, the dimensions of the “ball” and “bar” of the dumbbell-shaped molecular brushes were controlled. The growth and production of well-defined structures were verified by gel permeation chromatography (GPC), and the final dumbbell-shaped architectures were visualized by atomic force microscopy (AFM). This synthetic methodology represents a rapid and convenient route to unique macromolecular topologies.