Abstract

Organic semiconducting polymers are promising candidates for stretchable electronics for their mechanical compliance. Donor-Acceptor type conjugated polymers have been the key driver for the recent boost in device performance. Up to date, the effect of the conjugated backbone building block on the thermomechanical property of conjugated polymers has not been carefully studied, despite much work on their influence on the electronic property. In this talk, I will discuss our work on the structure and dynamics study of thin-film thermomechanical property relationship for donor-acceptor polymers with systematically varied donor units on the conjugated polymer ( DPP polymer). We utilized solution small angle neutron scattering to quantify backbone rigidity in solution. To characterize the thermomechanical performance, the pseudo-free standing tensile test was used to obtain the full stress-strain curve. The glass transition temperature was measured for both thin and bulk films using AC-chip calorimetry and DMA, respectively. Thin-film morphology was detected using AFM, UV-vis, and GIWAXS for further understanding. OFET devices were fabricated to test the electronic performance. The backbone structure and thermomechanical property relationship were established and applied to the design of new stretchable conjugated polymers.

Relevant publications:

(1)         Zhang, S.; Ocheje, M. U.; Luo, S.; Ehlenberg, D.; Appleby, B.; Weller, D.; Zhou, D.; Rondeau-Gagné, S.; Gu, X. Probing the Viscoelastic Property of Pseudo Free-Standing Conjugated Polymeric Thin Films. Macromol. Rapid Commun. 2018, 39 (14), 1800092. https://doi.org/10.1002/marc.201800092.

(2)         Zhang, S.; Ocheje, M. U.; Huang, L.; Galuska, L.; Cao, Z.; Luo, S.; Cheng, Y.; Ehlenberg, D.; Goodman, R. B.; Zhou, D.; et al. The Critical Role of Electron‐Donating Thiophene Groups on the Mechanical and Thermal Properties of Donor–Acceptor Semiconducting Polymers. Adv. Electron. Mater. 2019, 5 (5), 1800899. https://doi.org/10.1002/aelm.201800899.

(3)         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. https://doi.org/10.1002/macp.201900062.

(4)         Qian, Z.; Galuska, L.; McNutt, W. W.; Ocheje, M. U.; He, Y.; Cao, Z.; Zhang, S.; Xu, J.; Hong, K.; Goodman, R. B.; et al. Challenge and Solution of Characterizing Glass Transition Temperature for Conjugated Polymers by Differential Scanning Calorimetry. J. Polym. Sci. Part B Polym. Phys. 2019, 57 (23), 1635–1644. https://doi.org/10.1002/polb.24889.

(5)         Zhang, S.; Cheng, Y.; Galuska, L.; Roy, A.; Lorenz, M.; Chen, B.; Luo, S.; Li, Y.; Hung, C.; Qian, Z.; et al. Tacky Elastomers to Enable Tear‐Resistant and Autonomous Self‐Healing Semiconductor Composites. Adv. Funct. Mater. 2020, 2000663, 2000663. https://doi.org/10.1002/adfm.202000663.

(6)         Cao, Z.; Galuska, L.; Qian, Z.; Zhang, S.; Huang, L.; Prine, N.; Li, T.; He, Y.; Hong, K.; Gu, X. The Effect of Side-Chain Branch Position on the Thermal Properties of Poly(3-Alkylthiophenes). Polym. Chem. 2020, 11 (2), 517–526. https://doi.org/10.1039/C9PY01026B.

(7)         Cao, Z.; Li, Z.; Zhang, S.; Galuska, L.; Li, T.; Do, C.; Xia, W.; Hong, K.; Gu, X. Decoupling Poly(3-Alkylthiophenes)’ Backbone and Side-Chain Conformation by Selective Deuteration and Neutron Scattering. Macromolecules 2020, 53 (24), 11142–11152. https://doi.org/10.1021/acs.macromol.0c02086.

(8)         Galuska, L. A.; McNutt, W. W.; Qian, Z.; Zhang, S.; Weller, D. W.; Dhakal, S.; King, E. R.; Morgan, S. E.; Azoulay, J. D.; Mei, J.; et al. Impact of Backbone Rigidity on the Thermomechanical Properties of Semiconducting Polymers with Conjugation Break Spacers. Macromolecules 2020, 53 (14), 6032–6042. https://doi.org/10.1021/acs.macromol.0c00889.

(9)         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. https://doi.org/10.1002/adfm.202002221.

(10)      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. https://doi.org/10.1002/adfm.202100161.

Bio

Xiaodan Gu earned his Ph.D. from the Department of Polymer Science and Engineering at the University of Massachusetts 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. He is currently an assistant professor from the School of Polymer Science and Engineering at the University of Southern Mississippi. 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. He was awarded the NSF Career Award, ACS PMSE Young Investigator, ORAU Powe Junior Faculty Enhancement Award, a contributor to “Young Talents” special issue to Macro Rapid Comm, and “Emerging investigator” special issue for Polymer Chemistry.