Seminar Speaker: Dr. Xiaodan Gu, University of Southern Mississippi

Speaker Dr. Xiaodan Gu, University of Southern Mississippi

Title Harnessing Polymer Physics To Achieve Predictable Design of Soft Electronic Materials For Wearable Applications

Organic semiconducting polymers were widely studied due to their unique optoelectronic and mechanical property. They are the key component in various functional electronic devices, such as organic photovoltaic devices, flexible displays, wearable sensors, neuromorphic computing, and more recently bioelectronics. Despite tremendous progress being made in improving the charge carrier mobility and optimizing energy bandgap, the conjugated polymer’s physical property was not understood such as chain rigidity, molecular entanglement behavior, and glass transition phenomenon.  Such knowledge gap prevents the field from predictivity designing new conjugated polymers to meet the demand for future wearable needs.    

In my talk, I will provide an overview of our effort toward the predictive design of soft wearable electronics materials through unique thin-film-based experimental techniques and molecular dynamics simulations (in collaboration with W. Xia NCSU).  Through my talk, I will  1) discuss the use of thin-film mechanics for understanding mechanical property for sub 100nm polymeric thin film; 2) demonstrate the integrations of the thin film dynamics measurements and informatic to accurately predict the glass transition temperature as well as the mechanical property for conjugated polymers; 3) elucidate the role of the chain rigidity on polymer entanglement and thin-film fracture behavior; 4)discuss my perspective on the limitation of utilizing conjugated polymer as functional layers and potential pathways forward.  Additionally, I will discuss several applications of wearable devices based on the knowledge gained.

Selected Relevant works

• Qian, Z.; Cao, Z.; Galuska, L.; Zhang, S.; Xu, J.; Gu, X. Glass Transition Phenomenon for Conjugated Polymers. Macromol. Chem. Phys. 2019, 220 (11), 1900062. 
• Zhang, S.; Alesadi, A.; Selivanova, M.; Cao, Z.; Qian, Z.; Luo, S.; Galuska, L.; Teh, C.; Ocheje, M. U.; Mason, G. T.; et al. Toward the Prediction and Control of Glass Transition Temperature for Donor-Acceptor Polymers. Adv. Funct. Mater. 2020, 2002221, 2002221.  
• Zhang, S.; Alesadi, A.; Mason, G. T.; Chen, K.-L.; Freychet, G.; Galuska, L.; Cheng, Y.-H.; St. Onge, P. B. J.; Ocheje, M. U.; Ma, G.; et al. Molecular Origin of Strain‐Induced Chain Alignment in PDPP‐Based Semiconducting Polymeric Thin Films. Adv. Funct. Mater. 2021, n/a (n/a), 2100161.  
• Zhang, S., Koizumi, M., Cao, Z., Mao, K. S., Qian, Z., Galuska, L. A., Jin, L., & Gu, X. (2021). Directly Probing the Fracture Behavior of Ultrathin Polymeric Films. ACS Polymers Au, 1(1), 16–29.  
• Zhang, S., Cheng, Y., Galuska, L., Roy, A., Lorenz, M., Chen, B., Luo, S., Li, Y., Hung, C., Qian, Z., st. Onge, P. B. J., Mason, G. T., Cowen, L., Zhou, D., Nazarenko, S. I., Storey, R. F., Schroeder, B. C., Rondeau‐Gagné, S., Chiu, Y., & Gu, X. (2020). Tacky Elastomers to Enable Tear‐Resistant and Autonomous Self‐Healing Semiconductor Composites. Advanced Functional Materials, 2000663, 2000663 
• Galuska, L. A., Muckley, E. S., Cao, Z., Ehlenberg, D. F., Qian, Z., Zhang, S., Rondeau-Gagné, S., Phan, M. D., Ankner, J. F., Ivanov, I. N., & Gu, X. (2021). SMART transfer method to directly compare the mechanical response of water-supported and free-standing ultrathin polymeric films. Nature Communications, 12(1), 2347.  
• Machine Learning Prediction of Glass Transition Temperature of Conjugated Polymers from Chemical Structure. Under review.

Xiaodan Gu is currently a Nina Bell Suggs Endowed assistant professor from the School of Polymer Science and Engineering at the University of Southern Mississippi. He received his Ph.D. from the Department of Polymer Science and Engineering at the University of Massachusetts at Amherst in 2014, focusing on the self-assembly of block copolymers and their lithographic applications. Subsequently, he did a post-doctoral at the Stanford University and SLAC National Accelerator Laboratory, where he studied the morphology of roll-to-roll printed electronics using real-time X-ray scattering at various synchrotron beamlines. His current research interests revolve around various fundamental polymer physics phenomena related to conjugated polymers and their derivative devices. His group studies the structure, dynamics, and morphology of conjugated polymers and aims to link their molecular structures to their macroscopic properties through advanced metrology with an emphasis on scattering techniques. His research team’s effort was recognized by the NSF Career Award, DOE Early Career Award, ACS PMSE Young Investigator award, and ORAU Powe Junior Faculty Enhancement Award.