The heterogeneous and multifunctional characteristics of lignin is a paradox for its potential in polymer applications, despite its renewable and aromatic nature. We demonstrate a simple approach to the preparation of renewable lignin-grafted polymers via robust copper-free thermal click chemistry. High lignin content polymers were prepared between polymer pairs containing azide and alkyne groups with tunable compositions including PEG, PCL and PLA. (C) 2015 Elsevier Ltd. All rights reserved.