Synthesis, characterization and modification of azide-containing dendronized diblock copolymers

A series of dendronized diblock copolymers having rigid backbone and reactive surface were synthesized by ring-opening metathesis polymerization (ROMP) from dendronized norbornene derivatives using the second generation Grubbʹs catalyst. The bromine-terminated block of those rigid nanostructures has been converted to more reactive azide groups in one straightforward step. The resulting polymers were then functionalized by post-polymerization reaction with fullerene C60 (electron acceptor) using thermal [3 + 2] cycloaddition reaction or with porphyrin (electron donor) using copper-catalyzed “click chemistry”, the ultimate goal being the preparation of efficient polymeric materials for photovoltaic applications. While fullerene addition was not complete (approximately 50%) because of cross-linking reactions and steric hindrance on the dendrimers surface, Zn-porphyrin introduction went to completion clearly demonstrating the usefulness of click chemistry for polymer functionalization.