Although supramolecular polymers possess dynamic and reversible properties, their structures have inherent unpredictability due to the presence of non-covalent interactions. Therefore, finding new methods for controlling the structure of supramolecular polymers has become an important topic in their research field. In this study, two different monomers, AB2 and CD2, were synthesized. The AB2 monomer consists of a secondary ammonium salt-functionalized pillar[5]arene, while CD2 contains a neutral guest and two phenylene-21-crown-7 moieties. The AB2 monomer can self-assemble into supramolecular hyperbranched homopolymers [AB2]n through the secondary ammonium salt-host-guest reaction in chloroform solution. Upon the addition of CD2 to the AB2 system, the neutral guest in CD2 competes with the secondary ammonium salt and displaces it from the cavity of pillar[5]arene, resulting in the dissociation of the supramolecular hyperbranched homopolymers based on AB2. Simultaneously, the phenylene-21-crown-7 on CD2 can complex with the displaced secondary ammonium salt from AB2, leading to the formation of a new supramolecular alternating copolymer [AB2-CD2]n. This competitive self-sorting assembly principle enables the structural transformation of supramolecular polymers and provides a convenient approach for preparing supramolecular polymers with different structures and functions.

The related research work has been published online in "Macromolecular Rapid Communications" (2017, 38, 1600631) and selected as the cover article. The full text can be accessed at the following link: http://onlinelibrary.wiley.com/doi/10.1002/marc.201600631/abstract.