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Intelligent Design of Autonomous Materials

The Intelligent Design of Autonomous Materials Group welcomes competitive and enthusiastic applicants to conduct cutting-edge research at HKUST. Interested persons with theoretical or computational background in Applied Mathematics, Physics, Biophysics, Materials Science, Mechanical Engineering, or Chemical Engineering are encouraged to send enquiries to Rui's email address at

ruizhang@ust.hk

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Our Research

Our society is currently facing unprecedented challenges in health, energy, and environment. And there is a strong demand in new materials which are renewable, multifunctional, light-weight and can interact with human more safely and more intelligently. Soft materials are a promising candidate for the above purpose. The overarching goal of the Computational Soft Matter Group is to harness soft materials, such as active matter, multiphase or porous media, liquid crystals, polymers, colloids, and mechanical metamaterials, to design next generation, autonomous materials and soft machines.

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Specifically, our group will employ traditional and emerging computational methods, including machine learning, to propose novel soft materials with nontraditional functionalities, features and dynamics. Examples include active fluids with tailorable flow patterns, multiphase systems sensitive to specific stimuli, and origami materials with novel shape-changing behaviors in response to external fields. These new soft materials could find applications in soft robotics, wearable devices, space exploration, 4D printing, energy harvesting, smart buildings, sensing and diagnosis, and etc.

 

Our group strives to borrow the wisdom from biological systems and design synthetic materials and machines that are low-cost, green, biocompatible and intelligent. Our research is multidisciplinary, covering Physics, Biology, Chemistry, Materials Science, Chemical Engineering, and Mechanical Engineering.

Symmetry Breaking of Self-Propelled Topological Defects in Thin-film Active Chiral Nematics

Weiqiang Wang, Haijie Ren and Rui Zhang#

Phys. Rev. Lett. 132, 038301 – Published 17 January 2024

Active nematics represent a range of dense active matter systems which can engender spontaneous flows and self-propelled topological defects. Two-dimensional (2D) active nematic theory and simulation have been successful in explaining many quasi-2D experiments in which self-propelled +1/2 defects are observed to move along their symmetry axis. However, many active liquid crystals are essentially chiral nematic, but their twist mode becomes irrelevant under the 2D assumption. Here, we use theory and simulation to examine a three-dimensional active chiral nematic confined to a thin film, thus forming a quasi-2D system. We predict that the self-propelled +1/2 disclination in a curved thin film can break its mirror symmetry by moving circularly. Our prediction is confirmed by hydrodynamic simulations of thin spherical-shell and thin cylindrical-shell systems. In the spherical-shell confinement, the four emerged +1/2 disclinations exhibit rich dynamics as a function of activity and chirality. As such, we have proposed a new symmetry-breaking scenario in which self-propelled defects in quasi-2D active nematics can acquire an active angular velocity, greatly enriching their dynamics for finer control and emerging applications.

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