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Hyperbranched Oxime-Ester Covalent Adaptive Network for Recyclable Ultralow-Dielectric Epoxy
Xiaoyan Qiu1, Zhangqin Yang1, Bo Zhou1
1National Key Laboratory of Advanced Polymer Materials, Polymer Research Institute, Sichuan University, Chengdu, 610065, China.
Angewandte Chemie (International Ed. in English)
|October 18, 2025
Summary
We developed recyclable epoxy printed circuit boards (PCBs) using novel dendritic dynamic crosslinkers. These materials achieve ultralow dielectric loss for high-frequency electronics while enabling closed-loop recycling, significantly reducing e-waste and ecotoxicity.
Area of Science:
- Materials Science
- Polymer Chemistry
- Sustainable Electronics
Background:
- Epoxy thermosets are crucial for high-frequency electronics (5G/6G) but generate e-waste due to non-recyclability.
- Existing recyclable covalent adaptable networks (CANs) suffer from high dielectric losses at gigahertz (GHz) frequencies.
- A trade-off exists between recyclability and dielectric performance in electronic materials.
Purpose of the Study:
- To develop recyclable epoxy-based printed circuit boards (PCBs) with ultralow dielectric loss for high-frequency applications.
- To engineer novel generation-tunable dendritic dynamic crosslinkers for precise control over material properties.
- To reconcile the conflicting demands of circularity and high-frequency performance in electronic materials.
Main Methods:
- Synthesized generation-tunable dendritic dynamic crosslinkers via O-acylation of vanillin-derived aldoxime with phthalic anhydride.
- Fabricated graded-branched epoxy CANs with controlled nanomorphology, free volume, and steric confinement.
- Investigated dielectric properties, mechanical strength, flame retardancy, and recyclability of the developed PCBs.
Main Results:
- Achieved record-low dielectric constant (2.02) and loss (0.005) at 10 GHz.
- Demonstrated 71.53% improved X-band impedance matching and high tensile strength (256 MPa).
- Obtained V-0 flame retardancy and 98.9% reduction in ecotoxicity after closed-loop recycling at 80 °C.
Conclusions:
- Precision dendrimer synthesis and topology control enable recyclable PCBs with exceptional high-frequency dielectric performance.
- The developed materials offer a sustainable solution for next-generation electronics, addressing e-waste and performance requirements.
- This approach successfully reconciles the inherent trade-off between circularity and GHz-band performance.
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