Control over the Geometric Shapes and Mechanical Properties of Uniform Platelets via Tunable Two-Dimensional Living Self-Assembly

Abstract

It remains unexplored how the living self-assembly of small molecules can gain control over the geometric shapes and mechanical properties of the two-dimensional (2D) platelets fabricated therefrom. Herein, we report a tunable 2D living self-assembly method to control the geometric shape variety and mechanical properties of the resulting uniform 2D platelets. This new approach of using n-alkyl alcohols to connect a donor–acceptor (D–A) molecule into a 2D network via hydrogen bonding has a threefold effect on the formed 2D platelets. First, the intralayer molecular packing involving continuous hydrogen bonds between a D–A fluorophore and alcohols remains unaltered, thereby yielding the same optical properties and thermal stability to various 2D platelets. Second, the kinetic growth differentiation of the D–A fluorophore and alcohol in two dimensions depends on the interaction competition of alcohol with the D–A fluorophore against hexane (a poor solvent), engendering the alcohol-dependent 2D shape variety. Third, the interlayer interactions along the thickness of the platelet can be effectively modulated by the alcohol tails with different lengths that stretch out of each bilayer, thereby varying the mechanical properties of the 2D platelets, for which Young’s moduli and hardnesses decrease significantly with the increasing tail length of the alcohols.