Multiarm Star Polymers with a Thermally Cleavable Core: A "Grafting-from" Approach Paves the Way

Thermally cleavable multiarm star polymers containing thermo-reversible furan-maleimide cycloadduct-based core were synthesized using dendritic macroinitiators. Peripheries of dendritic macroinitiators were modified with bromine containing free radical initiators to obtain multiarm polymers by utilizing atom transfer radical polymerization (ATRP). Cleavage of thus obtained multiarm polymers was achieved via the retro Diels-Alder cycloreversion reaction of the furan-maleimide core at elevated temperatures. As an alternative approach, combination of multiarm polymers containing a furan and maleimide functional group at their core was attempted to realize that the steric bulk does not allow their formation. Hence the grafting-from route using a thermally fragmentable trigger containing multiarm initiators provides a plausible methodology for fabrication of such thermally cleavable multiarm polymeric materials. Syntheses of dendritic initiators, formation of star polymers as well as their fragmentation were followed by proton nuclear magnetic resonance spectroscopy and size exclusion chromatography. (c) 2016 Wiley Periodicals, Inc.