Research
MISSION
Understand the mechanics of soft materials
Explore new opportunities in material science
Topology engineering of polymer networks
A single polymer chain is as soft as living tissue and as strong as carbon fiber. However, rubber bands are weak, and carbon fibers are strong, even though both consist of carbon-carbon bonds. Can soft materials be as strong as carbon fiber? The answer lies in the molecular structure. In a soft material, polymer chains crosslink and entangle, forming a polymer network. Therefore, it is the topology of the polymer network that determines whether the soft material is strong or weak. More importantly, the topology of the polymer network can be engineered. Designing the network topology has enormous potential to achieve extreme material properties, poses fundamental questions in mechanics and material science, and opens new possibilities for diverse applications.
Related papers
"Multiscale stress deconcentration amplifies fatigue resistance of rubber", Nature, 624, 303-308 (2023) PDF SI Movie1 Movie2 Movie3 Movie4
“Fracture, fatigue, and friction of polymers in which entanglements greatly outnumber cross-links", Science, 374(6564), 212-216 (2021) PDF SI Movie1 Movie2 Movie3 Movie4
"Making Highly Elastic and Tough Hydrogels from Doughs", Advanced Materials, 2206577 (2022)
“Self-assembled nanocomposites of high water content and load-bearing capacity", Proceedings of the National Academy of Sciences, 119(32), e2203962119 (2022) PDF SI Movie1 Movie2
Modeling of soft materials
Modeling materials not only allows us to simulate behaviors—it provides a foundation of material development and insight into their design when they are simple and general. By using a simple and clean material system, we compare the prediction of our model and the experimental data, revealing unknown mechanisms in soft materials.
Related papers
“Polyacrylamide hydrogels. IV. Near-perfect elasticity and rate-dependent toughness", Journal of the Mechanics and Physics of Solids, 158, 104675 (2021) PDF
“Polyacrylamide hydrogels. V. Some strands in a polymer network bear loads, but all strands contribute to swelling", Journal of the Mechanics and Physics of Solids, 105017 (2022) PDF
"Polyacrylamide hydrogels. VI. Synthesis-property relation", Journal of the Mechanics and Physics of Solids, 105099 (2022)
“A chemical pump that transmits liquid fuel from a low-pressure tank to a high-pressure actuator", Advanced Intelligent Systems, 2100246 (2022) PDF SI Movie1 Movie2 Movie3
“Clustering transition in thermo-responsive micropillars", Small Structures, 2200023 (2022) PDF SI Movie1 Movie2
Multiscale structures
Nature has outstanding mechanical properties with its multi-scale structures, but many fabrication technologies are limited to a certain range of sizes. A fabrication technique capable of multi-scale structures (from nanometer to millimeter) mimics nature with unique advantages.
Related papers
“Artificial Perspiration Membrane by Programmed Deformation of Thermoresponsive Hydrogels", Advanced Materials, 32(6), 1905901 (2019) PDF SI Movie1 Movie2 Movie3 Front Cover
“Nonlinear Frameworks for Reversible and Pluripotent Wetting on Topographic Surfaces”, Advanced Materials, 29(7), 1605078 (2016) PDF SI Frontispiece Cover
“Microfluidic platforms with monolithically integrated hierarchical apertures for the facile and rapid formation of cargo-carrying vesicles”, Lab on a Chip, 15(2), 373-377 (2015) PDF
“Replication of flexible polymer membranes with geometry-controllable nano-apertures via a hierarchical mould-based dewetting”, Nature Communications, 5, 3137 (2014) PDF SI Movie1 Movie2
“Multiscale Transfer Printing into Recessed Microwells and on Curved Surfaces via Hierarchical Perfluoropolyether Stamps”, Small, 10(1), 52-59 (2014) PDF SI Inside Front Cover
Thermoelectric generators
Thermoelectric devices can convert low heat energy into electricity. Not only the value of ZT of the thermoelectric material but also the design of the thermoelectric generator plays a key role in performance.
Related papers
“Self-Powered Autonomous Wireless Sensor Node by Using Silicon-Based 3D Thermoelectric Energy Generator for Environmental Monitoring Application", Energies, 13(3), 674 (2020) PDF
“Design and Experimental Investigation of Thermoelectric Generators for Wearable Applications”, Advanced Materials Technologies, 1600292 (2017) PDF SI