SUBJECT: Ph.D. Dissertation Defense
BY: Haohui Zhang
TIME: Monday, August 15, 2022, 2:00 p.m.
PLACE: MRDC Building, 4115
TITLE: Physics-based Model that Couples Reaction, Diffusion, and Network Remodeling for Active Polymers
COMMITTEE: Dr. Yuhang Hu, Chair (GT ME)
Dr. H. Jerry Qi (GT ME)
Dr. Min Zhou (GT ME)
Dr. Ting Zhu (GT ME)
Dr. Sujit S. Datta (Princeton CBE)


For centuries, Nature has awed scientists with its rich repertoire of materials and systems that can dynamically adjust their structure and properties to adapt to the everchanging environment. The dynamic adaption of Nature’s living systems roots from a cascade of coordinated chemo-mechanical feedbacks. Learning from Nature, many synthetic dynamic materials have been developed. Wide ranging examples include various stimuli-responsive hydrogels and dynamic living polymers. Although noticeable attempts and efforts have been dedicated to studying the chemo-mechanical behaviors of Natural systems and synthetic systems that exhibit certain aspects of the adaptive performance as Natural systems, almost all the previous studies focus on the strict one-way chemo-to-mechanical or mechano-to-chemical transductions. The concurrent and fully coupled chemo-mechano-chemical behavior in nonequilibrium dynamic settings has rarely been explored, which is what living systems do to realize functions such as growth, healing, adaptation, evolution, etc. To fill this gap, in this proposed thesis, we will build thermodynamically consistent chemo-mechanical coupling models for the natural and synthetic soft active materials. We will start with building a general framework that couples large deformation, reaction and transport, and using this model to explore the deformation mechanism of stimuli-responsive hydrogels and quantitatively predict their responses in complex geometries and environmental conditions. Next, we will add the feature of dynamic bond breaking and formation into the model and use it to explore the growth mechanism of a recently developed dynamic polymer that involves concurrent transport, polymerization and network remodeling. Finally, we will add the light propagation coupling into the model, and use it to explore how the polymerization and possibly other photo-chemical reaction process are intertwined with the light propagation direction.