King Abdullah University of Science and Technology

Downward solar evaporation with multistage configurations is a promising off-grid solution for high-efficiency potable water production. However, a major, yet often overlooked, barrier to practical application is the significant, unquantified performance gap between laboratory benchmarks and field operation, arising from the complex environmental factors. To diagnose this gap, this work first introduces the Environmental Robustness Index (ERI), the ratio of field-to-lab normalized water productivity (P'), as an essential metric. A comprehensive framework is then developed to precisely quantify the effect of key environmental factors, including wind, sky cooling, and ambient temperature, on the ERI. Guided by the framework, we present the spectrally selective air lock strategy as a universal principle to suppress environmental heat losses and improve ERIs. Implementing this strategy significantly enhances downward solar evaporator's ERIs from 0.55 to 0.98, effectively closing the gap. This study establishes a framework for solar evaporation to move beyond reporting P'lab alone and utilize (P'lab, ERI) as the dual metrics for advancing real-world applicability.

High-density polyethylene’s (HDPE) chemical inertness, the foundation of its commercial success, renders it nearly impossible to chemically recycle. Furthermore, strict purity requirements limit mechanical recycling rates to ∼30% despite the legislative targets being 75%. Chemically recyclable polyolefin mimics containing cleavable ester linkages offer a solution, but their compatibility with commodity polyethylene waste streams remains unexplored, raising concerns that contamination could worsen rather than solve the global recycling crisis. Here, we demonstrate that HDPE-like polyesters (HDPE-like) exhibit complete miscibility with HDPE across all compositions (20–80 wt %), a crucial result given the expected difficulty to separate the HDPE-like from HDPE waste streams. Single melting transitions, cocrystallized lamellar structures, and retention of ductility confirm molecular-level mixing without mechanical failure. Strikingly, incorporation of just 20 wt %HDPE-like increases adhesion to aluminum by more than 10-fold (from 0.4 to 4.4 MPa), an effect that persists in postconsumer recycled HDPE, enabling upcycling of low-value waste into metal-laminate applications. Both components retain their recycling pathways: HDPE undergoes mechanical reprocessing, while HDPE-like achieves quantitative methanolysis to monomers that repolymerize with full property retention. By demonstrating that chemically recyclable polyesters can be miscible with, and functionally beneficial to, commodity polyolefins, this work establishes a dual-recycling framework where a contamination becomes a useful additive.