Sustainable acoustic metamaterials from recycled plastic bottles: A comprehensive review for circular noise control in the built environment

Noise pollution remains a major environmental and health concern, particularly at low frequencies where conventional insulation materials are bulky and inefficient. At the same time, the accumulation of plastic waste, especially from polyethylene terephthalate (PET) bottles, poses a critical sustainability challenge. This review bridges these two issues by systematically analyzing recent advances in acoustic metamaterials derived from recycled plastic bottles. Following a PRISMA-based methodology, eighty peer-reviewed studies were examined, covering resonant, porous, hybrid, and multilayer structures. Performance indicators such as sound absorption coefficient, transmission loss, and frequency bandwidth are critically compared across theoretical, numerical, and experimental approaches. Beyond acoustic metrics, the review integrates sustainability dimensions, including recyclability, life-cycle assessment (LCA), and life-cycle cost (LCC), positioning recycled-plastic-based metamaterials as eco-innovative solutions for building applications. The analysis highlights both the potential and the limitations of these materials: high tunability and circularity on one side, and unresolved challenges such as scalability, variability of waste feedstocks, fire safety, and standardization of testing on the other. A research roadmap is proposed to accelerate the transition from laboratory prototypes (TRL 3–4) to scalable, industry-ready solutions for the built environment. Overall, this work demonstrates that recycled plastic bottle-based acoustic metamaterials can simultaneously address noise pollution and plastic waste, aligning with the objectives of sustainable materials engineering. • Recycled PET bottles engineered into acoustic metamaterials for noise control • Low-frequency absorption and insulation achieved with compact resonant structures • Comparative review of theoretical, numerical, and experimental approaches • Circular economy integration through life-cycle and recyclability assessment • Identified challenges: scalability, waste variability, and test standardization.