Single-Step Solution-Phase Synthesis of Free-Standing Two-Dimensional Polymers and Their Evolution into Hollow Spheres

Interest in two-dimensional (2D) polymers has increased rapidly since the isolation of graphene. However, approaches to the preparation of graphene-like materials still face great challenges. Herein we report a facile method to prepare single molecular thick 2D polymers by simply running the polymerization reaction in a flask without the aid of any templates and postmodification techniques. The strategy is to use the triptycene scaffold, a rigid three-dimensional skeleton, as one monomeric unit to substantially suppress the interlayer interaction between the as-formed polymeric 2D monolayers. The new individual monolayered 2D polymers float freely in solution and can be further transferred onto solid surface for characterization. It is also found that the resulting 2D polymeric monolayers can further evolve into monolayered or multilayered hollow spheres, which might be regarded as a model for the transformation of graphene to fullerene.