Dynamic imine clipping has been shown to be an efficient method for assembling complex oligo(rotaxane) structures. In the present research program we are exploring the applicability of dynamic covalent chemistry as a means of constructing complex polymer architectures, as well as controlling their morphology and crosslinking.Expanding upon the previously reported dialkylammonium-templated rotaxane formation, combination of suitable imine precursors with a polyammonium polymer in solution leads to the spontaneous formation of oligorotaxanes, which brings about a marked change in both the length and rigidity of the mechanically interlocked oligomer. Thus, as shown by molecular dynamics simulation, as well as by NMR spectroscopy, a randomly coiled ammonium oligomer adopts a largely linear conformation upon formation of the polyrotaxane because of favorable p�p stacking interactions between the adjacent rotaxane rings which are separated from each other by 3.5�. The change in the overall dimensions of the molecules occurring upon rotaxanation could be maximized by employing suitable polymers, potentially leading to nanometer-scale elongations within single molecules.The inherently reversible nature of imine macrocycle formation serves as a convenient handle to create pH-switchable materials, where a change in acidity of the medium would induce either imine formation, or imine cleavage. Similar methodology could also be used for constructing sliding rotaxane and catenane crosslinks in polymers.

Dynamic imine clipping self-assembly in polymer chemistry

248th National Meeting (2014)

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