Hybrid materials are a particularly important class of nanomaterials as the combination of organic and inorganic species at the molecular scale leads to novel properties and functionalities. The strength and stiffness of these intrinsically porous and generally brittle materials scale with density, which is controlled by the underlying molecular structure and network connectivity. However, designing hybrid nanomaterials to maintain high levels of mechanical strength and stiffness remains a significant challenge that can ultimately limit the integration of these materials into emerging nanotechnologies ranging from microelectronics to antireflective coatings and molecular sieves. To address this challenge, we have exploited the fundamental dependence of the elastic properties on network connectivity and discovered hyperconnected network architectures, wherein a silicon atom’s connectivity within the network extends beyond its chemical coordination number, resulting in exceptional mechanical properties. We show the distinction between 4-fold and 5-fold connected architectures in Fig. 1. We initially predict the remarkable performance of hyperconnected architectures by modeling a 1,3,5-benzene hyperconnected material with molecular dynamic (MD) simulations and found that the hybrid network was stiffer than fully dense silica even at a lower density. Subsequently, we calibrated the MD model via synthesis and characterization of an intrinsically porous hybrid glass processed from 1,3,5(triethoxysilyl)benzene. Importantly, we show that novel synthesis routes to optimize a material’s mechanical properties are fundamentally limited by the underlying molecular architecture. A hyperconnected architecture, wherein an atom’s network connectivity exceeds its coordination number, is a new nanoscale design strategy to achieve exceptional mechanical properties for nanomaterials where the elastic properties are fundamentally controlled by the underlying network connectivity.

Hyperconnected network architectures as a new route to exceptional mechanical properties

253rd National Meeting (2017)

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