Computational Nanodynamics Laboratory

Our investigations thus far have helped to enable progress towards rapid discovery and design of bioinspired suprabiomolecular materials by establishing a knowledge base of their physical behavior relevant to applications beyond the biological milieu. Our work on self-assembly, mechanical behavior, and transport capabilities of polymer-peptide conjugates have paved the way for making nanoporous polymer thin films that have selective transport capabilities that mimic biological water and ion channels. These studies have shown that it is possible to control the hierarchical ordering of ring shaped peptides into tubes with tunable interior chemistry using simple mechanical forces, namely those arising from entropic elasticity of conjugated polymer chains. Vertically tunable pore chemistry then leads to unique transport capabilities that are challenging to achieve with polymers or carbon nanomaterials. Our investigations on microbially fabricated protein-based materials have explained mutation effects on sequence-property relationships in a range of protein-based materials, including functional amyloids such as curli nanofibers, bacterial gas vesicles, spider silk, titin and mussel-foot proteins. 

Our work on cellulose nanocrystals and nanocomposites have revealed size and geometry dependent mechanical properties of nature’s most abundant structural biopolymer, ascertaining the importance of nanoscale multi phasic materials design as a core biological principle. Our prior work focused understanding how the blending ratio of longer tunicate and shorter wood nanocellulose into all-cellulose thin films influenced their structure and mechanical properties. These investigations informed the synthesis of chiral (Bouligand) structures with interesting photonic properties that depend on the self-assembly process. Impressively, these films that form are transparent and can have mechanical properties comparable to mineralized biomaterials such as bone. (Natarajan et al. Advanced Functional Materials, 2018). The Bouligand structure also confers superior impact resistance over aligned or orthogonally layered cellulosic films as illustrated by coarse-grained molecular dynamics simulations.  

Our work on the mechanical behavior of thin films and nanocomposites has tackled the important problem of simulating interface and interphase behavior at extended length and time scales. A newly established scale bridging technique called energy renormalization ( Xia et al. Science Advances, 2019, Giuntoli et al. npj Computational Materials ,2021) developed for investigating polymer dynamics near surfaces with nanometer scale resolution has been instrumental in revealing mesoscale details that govern mechanical performance, while retaining crucial chemical details of specific polymers. Similar scale birding methods established for carbon nanomaterials are now being utilized to understand size-effects in bioinspired layer-by-layer composites arising from nanoconfinement. We are also extending our materials-by-design capabilities to composites beyond those that are inspired from nature, to explain surface and substrate effects in nano electronics, structural composites and coatings in the broader context of Integrated Computational Materials Engineering (ICME) and the Materials Genome Initiative (MGI). These tools have been instrumental in describing the mechanical behavior of polymers in extreme environments such as high-strain rate impact.