Synthesis of rotaxane cross-linked polymers with supramolecular cross-linkers based on γ-CD and PTHF macromonomers: The effect of the macromonomer structure on the polymer properties

Vinylic supramolecular cross-linkers (VSCs) consisting of gamma-cyclodextrin (gamma-CD) and terminal bulky macromonomers (TBMs) based on polytetrahydrofuran (PTHF) were designed, synthesized, and used to introduce rotaxane cross-linkers into vinyl polymers in order to endow the resulting rotaxane-cross-linked polymers (RCPs) with improved mechanical properties. Special attention was focused on the impact of the TBM structure on the properties of RCPs. VSCs, which formed in situ upon mixing gamma-CD and the TBMs in water, were added to radical polymerization systems based on N, N-dimethylacrylamide to afford the corresponding RCPs. These RCPs were substantially tougher than covalently cross-linked polymers (CCPs), indicating a strong impact of the VSCs on the mechanical properties of the RCPs. VSCs obtained from macromonomers with longer PTHF chains afforded tougher RCPs compared to RCPs derived from TBMs with shorter PTHF chains, which highlights the importance of the flexible region of the polymer chain at the cross-linking points. (C) 2017 Elsevier Ltd. All rights reserved.