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Autonomous indication of electrical degradation in polymers


Dielectric polymers are ubiquitous as electrical insulation in electronic devices and electrical systems. Electrical degradation of dielectric polymers tends to initiate catastrophic failure of numerous devices and systems, but its detection and early warning remain challenging. Here we report a general material strategy that signals the electrical degradation of dielectric polymers by autonomously presenting a visually discernible warning in the form of a pronounced colour change. This colour change is induced by the chromogenic response of molecular indicators blended with the polymer, which are chemically activated by the oxygen radicals generated in situ during the electrical degradation of the polymer. We unveil that the structural degradation and electrical properties of the dielectric polymer are quantitatively correlated with the colour difference. Such a chromogenic process is autonomous without the need of human intervention or other external energy, thus offering the convenience to lower or even eliminate the risk of dielectric failure.

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Fig. 1: Electrical-degradation-indicating materials and free-radical-induced chromogenic mechanism.
Fig. 2: Chromogenic response of active PDMS/1 to electrical degradation.
Fig. 3: Correlation between electrical degradation and colour change.
Fig. 4: Visualization of electrical-tree-induced polymer degradation.

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This work was supported by the National Key R&D Program of China grants 2018YFE0200100 (J. He, Q.L. and J. Hu) and the National Natural Science Foundation of China grants 51921005 (J. He and Q.L.). We thank G. Tian for her help with the UPLC-HRMS analysis and the isolation of activated indicators. We thank M. Zhou for her help with analysing the chemical structure of indolinooxazole (1′) by using NMR spectroscopy. We thank R. Hu for her help with the microscopic observation and elemental analysis of electro-degraded polymers by using SEM. We also thank Y. Xia, H. Yang and T. Tan for fruitful discussions.

Author information

Authors and Affiliations



Q.L. and J. He. conceived the idea. Q.L., X.H., S.Z., J. He, J. Hu, J.X., M.Y. and L.H. designed the experiments. X.H., S.Z. and P.Z. carried out the experiments. X.H. and Y.Z. performed the simulations. X.H., S.Z., P.Z., J.X., M.Y., L.H., Q.L., J. He and J. Hu analysed the data. Q.L., X.H., S.Z. and J. He wrote the paper. All authors discussed the results and commented on the paper.

Corresponding authors

Correspondence to Qi Li or Jinliang He.

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Nature Materials thanks Gregory Sotzing, Daniel Q. Tan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Notes 1–8, Figs. 1–50, Schemes 1–7 and Tables 1–8.

Supplementary Video 1

ACN solution of spirooxazine (1) (left) and ACN solution of BPO (right) were preheated to 80 °C. After BPO/ACN was added to 1/ACN, the mixed solution immediately changed from light blue to yellow, indicating that the chromogenic reaction was instantaneously completed.

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Huang, X., Zhang, S., Zhang, P. et al. Autonomous indication of electrical degradation in polymers. Nat. Mater. (2023).

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