Recently, the Tang research group from the Frontier Science Center for Transformative Molecules at Shanghai Jiao Tong University has achieved significant progress in the field of polar cyclobutane-functionalized polymers. The team developed an innovative strategy that enhances both toughness and on-demand degradability in end-linked polymer networks by incorporating a non-cleavable cyclobutane-fused tetrahydrofuran mechanophore. This work, published in Nature Communications under the title "Cycloreversion-enhanced toughness and degradability in mechanophore-embedded end-linked polymer networks," presents a breakthrough in designing advanced functional materials. As cross-linked polymer networks find increasing applications in biomedical devices and flexible electronics, there is growing demand for materials that combine excellent mechanical strength with triggered, on-demand degradation. Mechanical chemistry leverages force-induced bond cleavage to generate reactive intermediates, enabling internal chemical responses that can enhance material performance. However, conventional approaches often alter the network topology and complicate large-scale fabrication. Moreover, introducing cleavable mechanophores such as cyclobutane derivatives into end-linked networks can lead to premature activation, creating defects that compromise mechanical integrity. To address this challenge, the Tang group designed a novel end-linked polymer network incorporating a non-cleavable cyclobutane-fused tetrahydrofuran mechanophore into the polymer backbone. This design enables simultaneous enhancement of both toughness and degradability without modifying the intrinsic chemical composition or network structure. The dual improvement arises from the force-triggered ring-opening reaction of the mechanophore, which simultaneously releases hidden chain segments and exposes acid-labile enol ether units. Compared to traditional materials, the resulting single-network polymer exhibits threefold higher toughness and tenfold greater fracture energy. Notably, after bulk ball-milling activation, the mechanophore undergoes ring-opening, exposing enol ether groups that dramatically accelerate degradation under acidic conditions. This allows for precise control over material breakdown, enabling on-demand disassembly. The researchers synthesized three types of dienes—C1 (with cleavable mechanophore), C2 (without mechanophore), and C3 (with non-cleavable cyclobutane-fused tetrahydrofuran mechanophore)—which exhibit similar reactivity, ensuring comparable network structures when polymerized in the same ratio. The resulting polymer networks PN1–PN4 differ only in the mechanophore type at the cross-linking sites. Mechanical testing revealed a clear trend: PN1 < PN2 < PN3 < PN4 in terms of tensile strength, elongation at break, and toughness (Figure 2b, 2d). Importantly, all networks displayed similar Young’s moduli (Figure 2c), indicating comparable cross-link density and network architecture. This consistency confirms that the observed mechanical differences stem solely from the mechanophore design. Rivlin–Thomas analysis of notched films under shear deformation further demonstrated that PN4’s fracture energy was ten times that of PN2, highlighting the effectiveness of the mechanophore in enhancing toughness. Dynamic mechanical analysis showed that PN1–PN4 exhibited similar storage moduli (G’), low loss moduli (G’’), and tan δ values below 1 (Figure 3a–b), confirming stable elastic behavior. Temperature sweeps revealed consistent mechanical stability across all samples (Figure 3c). Additionally, the networks showed similar swelling ratios (Figure 3d), gel content (Figure 3e), and glass transition temperatures (Tg) (Figure 3f), further supporting their structural similarity. The enhanced degradability was demonstrated through ball-milling and acid hydrolysis experiments. After 8 hours of ball milling at 50 Hz, PN4 transformed into a pale gray solid (Figure 4c). When exposed to TFA/H₂O (10:1, v/v), PN4′ dissolved completely within 10 minutes (Figure 4d, bottom), while PN2′ remained turbid (Figure 4d, top). Quantitative analysis revealed that PN4′ showed a sharp decrease in insoluble residue, whereas PN2′ showed minimal change (Figure 4e). Size-exclusion chromatography (SEC) of the hydrolyzed products showed a strong peak in the low molecular weight region for PN4′, indicating extensive chain scission (Figure 4f). ¹H NMR spectroscopy revealed a distinct peak at 9.8 ppm in PN4′, confirming the formation of aldehyde groups (Figure 4g). High-resolution mass spectrometry (HR-ESI-MS) further identified the presence of enol ether-derived fragments, providing direct evidence of mechanophore ring-opening (Figure 4h). In summary, this study demonstrates that non-cleavable cyclobutane-fused tetrahydrofuran mechanophores can simultaneously enhance toughness and enable on-demand degradation in single-network polymer systems. The dual functionality results from force-induced ring-opening, which releases hidden chain segments and generates acid-labile enol ether units. The resulting materials exhibit threefold higher toughness and tenfold greater fracture energy, without sacrificing elasticity or thermal mechanical stability. Ball-milling activation triggers the ring-opening reaction, significantly accelerating degradation under acidic conditions. This work establishes a powerful design principle for next-generation smart materials that combine high performance with precise degradation control. The research was supported by the National Natural Science Foundation of China and the Central University Basic Research Fund. The corresponding author is Associate Professor Shan Tang from the Frontier Science Center for Transformative Molecules at Shanghai Jiao Tong University. The first author is Zhiang Li, a Ph.D. student in the class of 2023. Shan Tang is a PI at the Frontier Science Center for Transformative Molecules, a Long-term Track Assistant Professor, and a doctoral supervisor at Shanghai Jiao Tong University. He earned his B.S. from Wuhan University in 2012 and Ph.D. in 2017, followed by postdoctoral research at the Weizmann Institute of Science (Israel) and the University of Tokyo (Japan). To date, he has published 8 papers in J. Am. Chem. Soc., 6 in Angew. Chem. Int. Ed., 5 in Nat. Commun., and other top journals, with over 7,700 citations and an h-index of 44. He currently leads a research group actively recruiting Ph.D. students for Fall 2026 via the “application-evaluation” system. Candidates with backgrounds in polymer chemistry, organometallic chemistry, or organic synthesis are encouraged to apply. For details, visit: https://fsctm.sjtu.edu.cn/info/1047/6054.htm. Interested applicants should send their CVs to [email protected]. Paper link: https://doi.org/10.1038/s41467-025-68268-1