Resonant Tender X-ray Scattering for Disclosing the Backbone Conformation of Conjugated Polymers

Journal Article · Thu Jun 26 00:00:00 EDT 2025 · Macromolecules

DOI:https://doi.org/10.1021/acs.macromol.4c03107· OSTI ID:2572420

Wang, Yunfei ^[1]; Chan, Ka Hung ^[2]; Freychet, Guillaume ^[3]; Wąsik, Patryk ^[4]; Zhang, Song ^[5]; Cao, Zhiqiang ^[5]; Gu, Xiaodan ^[5]

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1. University of Southern Mississippi, Hattiesburg, MS (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Hong Kong University of Science and Technology (HKUST), Kowloon (Hong Kong)
3. Brookhaven National Laboratory (BNL), Upton, NY (United States); University Grenoble Alpes CEA LETI (France)
4. Brookhaven National Laboratory (BNL), Upton, NY (United States)
5. University of Southern Mississippi, Hattiesburg, MS (United States)

The backbone conformation of conjugated polymers (CPs) is essential to their performance in electronic applications. Contrast-variation small-angle neutron scattering (CV-SANS) techniques were used to assess the CP’s backbone conformation, which relies on synthesis of deuterated polymers. Such a technique has been proven mature and effective. One drawback is that deuteration labeling might subtly alter polymer’s physical properties due to structural modifications. To address these challenges, we introduce a novel approach utilizing tender Xray scattering near the sulfur K-edge to distinctly evaluate the backbone versus whole chain conformation for a low-bandgap donor−acceptor CP, poly[(5,6-difluoro- 2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-dialkyl-2,2′;5′,2″;5″,2‴-quaterthiophen-5,5‴- diyl)] (PffBT4T). For PffBT4T dissolved in trimethylbenzene (TMB), the sulfur K-edge is identified at approximately 2477 eV using near-edge X-ray absorption fine structure spectroscopy (NEXAFS). Tender X-ray scattering conducted at presulfur K-edge and on-sulfur K-edge at elevated temperatures facilitated the distinction between the backbone and whole chain conformations. The results demonstrate that for highly flexible polymer, the backbone’s persistence length could be lower than that of the whole chains, suggesting a more flexible backbone. This rapid, label-free method enhances our ability to characterize CP’s backbone conformation efficiently, offering significant implications for the design and optimization of CPs for advanced electronics.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: National Science Foundation (NSF); US Department of Energy; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Scientific User Facilities Division (SC-22.3 ); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC02-05CH11231; SC0012704; SC0022050
• Other Award/Contract Number: DMR-2047689
• OSTI ID: 2572420
• Alternate ID(s): OSTI ID: 2572795; OSTI ID: 2583929
• Report Number(s): BNL--228447-2025-JAAM; https://escholarship.org/uc/item/9qn9068q; ark:/13030/qt9qn9068q
• Journal Information: Macromolecules, Journal Name: Macromolecules Journal Issue: 13 Vol. 58; ISSN 1520-5835; ISSN 0024-9297
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Conformation
Energy
Scattering
Sulfur
X-ray scattering