Dynamic Covalent Networks of Molecular Clusters for Hard and Impact-Resistant Glass with Feasible Processability

The polymeric organic glass suffers from the intrinsic tradeoffs among mechanical strengths, hardness, and impact resistance from their chain topologies, limiting their extensive applications. Herein, a polymer-free approach is developed for the fabrication of glass by crosslinking sub-nm particle using dynamic covalent bonds. The sub-nm polysilsesquioxane (POSS) particle is crosslinked by the dynamic boronic ester bonds when 1,4-phenylenediboronic acid is doped. The high crosslink density with homogeneous distribution of POSS endows the fabricated films with high elastic modulus (1.79 ± 0.43 GPa), hardness (0.36 ± 0.03 GPa), and transparency (>89.5% transmittance). The dynamic feature of the network enables excellent impact resistance beyond typical polymers by showing highenergy dissipation capacity (258.14 J cm^-3). The dynamic network also grants feasible processability that films with thickness as 1.3 µm can be fabricated through simple hot press. Moreover, due to the enriched B─O bonds and hydroxyl groups, high adhesive strengths as 8.20 ± 0.98 MPa for single lap shear strength on typical glass substrate can be achieved. This study provides new chemical systems to the design of glass with the capability to achieve balanced comprehensive performance in hardness, adhesiveness, (re)processability, and impact resistance besides its inherent high mechanical strength and transparency.