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Abstract The Mesozoic subduction history of the Paleo‐Pacific plate below the East Asian margin remains contentious, in part because the southern part is poorly understood. To address this, we conducted a sediment provenance study to constrain Mesozoic subduction history below West Sarawak, Borneo. A combination of detrital zircon U‐Pb geochronology, heavy minerals, trace element, and bulk rock Nd isotope data were used to identify the tectonic events. The overall maturity of mineral assemblages, dominantly felsic sources, abundant Precambrian‐aged zircons, and low εNd(0) values (average −13.07) seen in Late Triassic sedimentary rocks suggest a period of inactive subduction near Borneo. Slab shallowing subduction occurred between 200 and 170 Ma based on subdued magmatism and tectonic compression across West Sarawak. From c. 170 to 70 Ma there was widespread magmatism and we interpret the Paleo‐Pacific slab steepened. Collectively, we show the Paleo‐Pacific plate subduction had variable slab dip histories in Borneo. 

Abstract Lignin is an aromatic‐rich biomass polymer that is cheap, abundant, and sustainable. However, its application in the solid electrolyte field is rare due to challenges in well‐defined polymer synthesis. Herein, the synthesis of lignin‐graft‐poly(ethylene glycol) (PEG) and its conductivity test for a solid electrolyte application are demonstrated. The main steps of synthesis include functionalization of natural lignin's hydroxyl to alkene, followed by graft‐copolymerization of PEG thiol to the lignin via photoredox thiol‐ene reaction. Two lignin‐graft‐PEGs are prepared having 22 wt% lignin (lignin‐graft‐PEG 550) and 34 wt% lignin (lignin‐graft‐PEG 2000). Then, new polymer electrolytes for conductivity tests are prepared via addition of lithium bis‐trifluoromethanesulfonimide. The polymer graft electrolytes exhibit ionic conductivity up to 1.4 × 10⁻⁴ S cm⁻¹ at 35 °C. The presence of lignin moderately impacts conductivity at elevated temperature compared to homopolymer PEG. Furthermore, the ionic conductivity of lignin‐graft‐PEG at ambient temperature is significantly higher than homopolymer PEG precedents.