Summary:Natural and engineered structural (load-bearing) nanocomposites often try to exploit microphases that are confined in nanoscale dimensions to achieve remarkable mechanical properties. However, the emergent performance of these materials depends strongly on both the chemistry of the interfaces and the microstructure of the material system, which complicates their design. In this talk, I will present a new computational materials-by-design paradigm for understanding phenomena occurring at such disparate scales. I will discuss several cases where the coupling between nanostructure and chemical structure will lead to intriguing phenomena, such as polymers with more or less identical bulk properties exhibiting contrasting behavior under nanoconfinement in thin films. Drawing an analogy between thin films and nanocomposites, I will illustrate how understanding thin film simulations help us design better load-bearing nanocomposites with nanocellulosic fillers.