Abstract
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 X-ray 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.
| Original language | English |
|---|---|
| Pages (from-to) | 6865-6871 |
| Number of pages | 7 |
| Journal | Macromolecules |
| Volume | 58 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jul 8 2025 |
Funding
Y.W. and X.G. thank the National Science Foundation under ward number DMR-2047689 for supporting this work. This research used the Soft Matter Interfaces Beamline (SMI, Beamline 12-ID) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. C.Z. acknowledges partial support from the U.S. Department of Energy for the scattering experiments in this work, under Award No. DE-SC0022050. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. Y.W. was supported in part by an ALS Collaborative Postdoctoral Fellowship. Y.W. and K.H.C. were also supported in part by an ALS Doctoral Fellowship in Residence. The authors thank Dr. Zhengxing Peng for assistance with RSoXS. The authors thank Dr. Zhaofan Li for assistance with schematic in Figure 4. Y.W. and X.G. thank the National Science Foundation under ward number DMR-2047689 for supporting this work. This research used the Soft Matter Interfaces Beamline (SMI, Beamline 12-ID) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. C.Z. acknowledges partial support from the U.S. Department of Energy for the scattering experiments in this work, under Award No. DE-SC0022050. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. Y.W. was supported in part by an ALS Collaborative Postdoctoral Fellowship. Y.W. and K.H.C. were also supported in part by an ALS Doctoral Fellowship in Residence. The authors thank Dr. Zhengxing Peng for assistance with RSoXS. The authors thank Dr. Zhaofan Li for assistance with schematic in .