Novel main-chain polyrotaxanes synthesized via ATRP of HEMA initiated with polypseudorotaxanes comprising BriB-PEG-iBBr and α-CDs

A novel strategy for the preparation of main-chain polyrotaxanes with lengthily tunable PHEMA as outer bulky stoppers was described in the present study. Polypseudorotaxanes made from the self-assemblies of a distal 2-bromoisobutyryl end-capped PEG with a varying amount of α-CDs in aqueous media were used as macroinitiators in situ to initiate the ATRP of HEMA catalyzed by Cu(I)Br/PMDETA at room temperature. The resulting polyrotaxanes were characterized in virtue of 1H NMR, GPC, FTIR, XRD and DSC analyses. It demonstrated that the target polyrotaxanes were successfully synthesized and both the in-chained number of HEMA and the threaded number of α-CDs were adjustable to some extent. As the active Br groups held at two terminals and combining the unique properties of general polyrotaxanes with that of block copolymers, these supramolecular polymers show the potential as macroinitiators used for new ATRP polymerizations.