Sliding Supramolecular Polymer Brushes with Tunable Amphiphilicity: One-Step Parallel Click Synthesis and Self-Assembly

A one-step parallel grafting strategy is presented to readily prepare multifunctional complex macromolecules and miktoarm polymer brushes. Typically, a series of amphiphilic sliding supramolecular polymer brushes (SSPBs) were synthesized with cyclodextrin-based polyrotaxanes (Pits) as backbones. The amphiphilicity of SSPBs could be facilely tuned by the feed ratio of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic palmitoyl (C16) side chains. Click chemistry of Cu(I)-catalyzed azide-alkyne cycloaddition was employed as the parallel coupling reaction, and high grafting density (ca. 18 side chains immobilized on each a-cyclodextrin ring) and click conversion (similar to 100%) was achieved in a short reaction time (several minutes to 3 h). The SSPB with close proportion of PEG to C16 miktoarms showed balanced amphiphilicity and could aggregate into a Janus film at the interface of hexane and water, which was confirmed with a dye-labeling method and fluorescence measurements. The amphiphilic SSPBs could also assemble into microporous films on mica surfaces via spin-coating. The formation of the superstructured films was proved to be affected by the relative humidity, rotational speed of spin-coating, and composition of SSPBs.