The global plastic waste crisis persists as a pressing environmental challenge, with conventional degradation methods revealing fundamental technical constraints. Current industrial-scale recycling approaches suffer from downcycling effect, restricted applicability, and concomitant microplastic generation, [1,2] which underscores the urgent demand for transformative recycling paradigms that harmonize operational simplicity, economic feasibility, and minimal resource expenditure.

Sunlight-drive decomposition represents a revolutionary paradigm, which operates under ambient conditions with near-zero energy input, positioning a scalable and environmentally benign management solution. [3] However, achieving complete decomposition while maintaining essential material performance constitutes a critical technological hurdle.

we present a transformative materials design strategy as a potential solution to the problem. This design philosophy stems from our previous discovery that a polydiacetylene containing short carboxylic acid side groups undergoes complete degradation into small molecules under sunlight in either air or aqueous environments, primarily through the cleavage of its C=C and C≡C bonds in the backbone. [4] Intriguingly, the topochemical polymerization mechanism inherent to polydiacetylenes is particularly advantageous for crystalline engineering plastics with regularly aligned polymer strands. Using industrial crystalline engineering plastic polyamide 6/10 (nylon 6/10, or PA610) as a model system, our design introduces diacetylene moieties within the strands of PA610 while maintaining the commercial-grade properties of the materials in terms of mechanical properties and transparency. When exposed to sunlight, the inter-chain topochemical polymerization among adjacent diacetylene units occurs, creating a crosslinked network embedding photodegradable elements in both crosslinkers and polymer strands. The derived material then completely degrades in natural environment within 5 months. 

This sunlight-responsive switching mechanism elegantly reconciles the conflicting requirements of structural robustness during service life and controlled degradability at end-of-life, establishing a new paradigm for sustainable materials engineering.