Solution and solid-state properties of mechanically linked polycarbonates

Solution and solid-state properties of novel mechanically linked polyearbonate copolymers are reported and compared to corresponding properties of a reference copolymer with identical chemical composition but no mechanical linkages. The unperturbed dimensions of the catenane copolymers in solution are smaller than for bisphenol A polycarbonate homopolymer, presumably reflecting favorable specific interactions between bisphenol A and catenane units. A difference is observed between the mechanically linked and unlinked analogues, pointing to a specific effect of the mechanical linkage. Crystallinity measurements suggest a segmented composition for the copolymers, consistent with the solid-state synthesis. The melting point of the catenane copolymers is lower than that of the bisphenol A polycarbonate homopolymer because of a copolymer effect. The melting point of a mechanically linked copolymer is higher than of the unlinked analogue, presumably because of the additional mobility in the melt introduced by free macrocycle chain ends vs interlocked catenane units.