The hydrogen bond (H-bond) is an essential element of many materials including DNA, proteins, hydrogels and molecular self-assemblies. Despite existing knowledge of energy transport in some large protein systems, a systematic understanding of nanoscale thermal transport across H-bonded materials and, in particular, the role of H-bonds is lacking. The knowledge gap has hindered the understanding of heat transfer in living systems and development of novel biomaterials, e.g. synthetic spider silk, with extraordinary thermal properties. To address these critical challenges, this project investigates a suite of H-bonded materials including protein secondary structures and organic-inorganic interfaces, using state-of-the-art computational approaches combined with experimental validations. The research outcomes will accelerate design, development and deployment of novel H-bonded materials with tunable thermal properties, to meet the increasing needs for biocompatible, multifunctional materials in a wide range of areas including bio-implantation, tissue regeneration, cancer treatment, and energy storage. This project also seeks to achieve three societally relevant outcomes including (1) broadening participation of Female Native American students in engineering through two mentoring programs; (2) fostering skills of materials modeling among undergraduate students using a 3D Printing Challenge and a Fellowship program; and (3) conveying essential concepts of biomaterials and thermal management to high school students and the general public through outreach activities.
Building upon recent progress in advanced phonon transport theory and vibrational mode analysis, this project systematically reveals the role of H-bonds in thermal transport across several representative building blocks of H-bonded materials including nanocrystals (e.g. protein beta-sheets), nanowires (e.g. protein alpha-helices and 3-10 helices) and interfaces. By using molecular dynamics simulations and functional theory calculations, the investigations quantifies anisotropy of thermal conduction in the H-bonded building blocks in association with several structural and environmental factors including the H-bond connectivity (e.g. alpha helices vs. 3-10 helices), the side chain chemistry and size, and the solvation. Particular emphasis is given to understanding how different amino acid sequences can affect thermal conductivities and transport characteristics including phonon density of states, group velocities, and lifetimes. New physical insights are generated regarding: (1) how H-bond networks of different forms contribute to nanoscale thermal transport; and (2) how thermal transport in H-bonded materials differs from that in other 1D (e.g. nanotubes), 2D (e.g. graphene) and 3D materials that have no H-bonds. The achieved knowledge base enables development of new synthetic silk with highly conductive building blocks as well as novel H-bonded interfaces that are made, characterized and compared with existing materials for validation of the theory.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
