Mechanically Linked Polycarbonate

The synthesis, by solid-state copolymerization, and characterization of the first polycatenanes
based on a commercial polymer are reported. Various amounts of a benzylic amide [2]catenane, the
corresponding macrocycle, and a rigid bisphenol fluorene derivative have been quantitatively and
homogeneously incorporated into bisphenol A polycarbonate. The resulting copolymers were characterized
by size exclusion chromatography coupled with viscosimetry, 1H NMR, differential scanning calorimetry,
and dynamic mechanical analysis. The unexpectedly small influence of [2]catenane incorporation on the
glass transition temperature of the copolymers points to remarkable internal mobility of the catenane
comonomer rings. A new relaxation linked to the flexible catenane units is also observed. The studies
represent a detailed structural characterization of a polymer containing small amounts of mechanical linkages
in its backbone and demonstrate that significant effects can be induced by doping conventional polymers
with small percentages (2−6% of repeat units) of flexible catenanes.